--- title: Russia Might Be Reactivating a Secret Soviet Submarine Base description: "From above, you wouldn't spot the entrance to Objekt 825. In fact, you wouldn't know it was there at all. Flying over the town of Balaklava, in Crimea, you might look down on Mount Tavros, the sloping Baydar Valley, a pretty bay lined with pontoons.\n\nYou'd never know that sprawled beneath the mountain is a top-secret submarine base. And of course, that's just how the Soviets intended it.\n\nFirst opened in 1957, Objekt 825 was born from deep Cold War tensions – hewn from the mountain rock to shelter Soviet submarines. Now mothballed, it's become a museum, where paying visitors walk its tunnels with passing interest. A fascinating relic of the past, you might think.\n\nBut Objekt 825 might not be the remnant it appears. Because if its position in the Black Sea carried strategic weight during the Cold War, it's no less significant now. A handy hideaway on Ukraine's south coast, right when Russia is struggling to protect its Black Sea fleet.\n\nAnd there are distinct rumblings that far from being forgotten, this former submarine base is about to be awoken.\n\nIn February 2025, images emerged showing two new floating barriers at the entrance to the harbour. Barriers that would only exist if the Russian state had something in there that it desperately wanted to protect.\n\nIf this is true, Objekt 825 could be making an unexpected comeback.\n\n## A Strategic Hub\n\nToday, Balaklava and Objekt 825 sit within occupied Ukraine, on the Crimean Peninsula. This area was annexed by Russia in 2014, but it's been a fiercely fought-over area for centuries. Linking Europe with Asia, and within easy reach of Africa and the Mediterranean, it's the centre of a strategic spider's web.\n\nWe don't need a full history lesson here, but to give an idea of the political landscape, in the last century alone Crimea has been controlled by the Romanovs, Tatars and Nazis, as well as the Soviet Union, Ukraine, and the present-day Russian Federation. For generations beyond this, the port of Balaklava has been a waypoint for both civil and military maritime traffic.\n\nIt's small wonder, then, that as the world's superpowers stood among the lingering wreckage of World War Two, and the Cold War began to ramp up, this coastal spot was chosen as the perfect location for a new submarine base.\n\nPlans for what was codenamed \"Objekt 825 GTS\" were first created way back in 1947, when it was nothing more than an idea. At this time, sensitive to the risk the Cold War posed, Soviet leader Joseph Stalin entrusted officer Lavrentiy Beria with a special task: find the best possible site for a submarine maintenance complex. Ideally, somewhere hidden away, but conveniently located for the launch of a retaliatory attack.\n\nBeria's search took years, but finally, in 1953, he locked on to the ideal location. The natural geography of Balaklava Bay meant that its narrow, winding inlet, with steep hillsides, could be easily defended and disguised. This was a base at which submarines could both survive an attack, and launch one of their own.\n\nBy this time, Stalin had died and in the turmoil that followed, the Cold War was entering a new low. Both the United States and the Soviet Union were already growing their nuclear arsenal. On top of this, the Soviets began heavily investing in expanding their naval forces.\n\nYet the cataclysmic fallout of Hiroshima and Nagasaki, almost a decade earlier, had proven just how devastating a nuclear bombing could be. If such an event took place over Balaklava, its natural route into the ocean highway would be blocked. Expensive submarines could be lost. It would be a major blow to the Soviets' Black Sea Fleet.\n\nIn a nutshell, if someone did get wind of where they were, the Soviet submarines would be sitting ducks. The natural solution? Hide them.\n\nBuilding the entire facility underground would not only thwart any pesky spy satellites. It would also allow submarines to enter and exit Objekt 825 while completely submerged, making them almost invisible. The tell-tale exit hole, leading out to sea on the mountain's northern side, could be masked with camouflaged netting.\n\n## Hidden in Plain Sight\n\nAs you'd expect, it's not easy to hide an entire military base beneath a mountain. Building Objekt 825 was quite the endeavour.\n\nOvernight, the sleepy town of Balaklava became a construction zone, flooded with workers and engineers. This meant major upheaval for Balaklava's residents. But in the outside world, nobody knew it was going on at all.\n\nBecause yes, if the build itself wasn't challenging enough, the whole operation had to be carried out in secret. The site was immediately classified, becoming a closed city and eventually vanishing from maps for the next fifty years.\n\nObviously, this wasn't openly talked about – at least, not beyond the barbed wire fence. The only sign that something serious had shifted was a sudden and stringent tightening of security around the town.\n\nPhotography was banned, and along with camouflaged observation towers, checkpoints popped up to detain would-be visitors. If you were caught trying to stroll into Balaklava, you'd better have a good reason.\n\nEven the residents were all-but locked down, with restrictions extending to their friends and family. Never mind if your Auntie Maria lived in Balaklava, you wouldn't be popping along for an impromptu cup of tea – or a samovar – any time soon. At least, not unless you had the reams of paperwork needed for a short-term visit.\n\nWith this circle of secrecy pulled tight around the town, construction on Objekt 825 began. A special unit – numbered 528 – was formed to oversee the creation of the underground sub base. Drawing together engineers and personnel from the Black Sea Fleet, 528 was responsible for the ambitious excavation and construction work.\n\nBut the notion of subterranean builds definitely wasn't new to the Soviet government. In the closed city of Sevastopol alone, a veritable rabbits' warren of underground structures and catacombs had been in place for decades.\n\nIn 'Declassified Crimea', Khorsun Dmitrievich writes that the area beneath Sevastopol is estimated to encompass between 315,000 and 350,000 square kilometres. This includes, \"more than 600 bunkers, of which only about half are statistically registered. About 100 underground structures belong to the Black Sea Fleet\".\n\nAcross Russia, hundreds of kilometres of nuclear-proof tunnels were ready and waiting.\n\nYet building these structures was deeply labour-intensive. Construction on Objekt 825 alone took eight years of backbreaking work. It's said that underground work cost 67 million Soviet rubles, with equipment and life support systems adding another 65 million rubles to that figure.\n\nCreating the space they needed involved removing an incredible 120,000 tons of solid mountain to make way for a vast subterranean network of chambers and tunnels. This could only be done by successive drilling and blasting, using a similar method to hard rock mining.\n\nWorkers would drill deep shafts in the rock, before packing them with explosives and, we hope, retreating to a safe distance. The resulting void could then be cleared of its rubble and a concrete formwork built to reinforce the structure. To preserve secrecy, supplies arrived – and rock was cleared out and dumped – under cover of darkness.\n\nA hidden lair inside a mountain, with barges silently stealing in at night? It's all wonderfully James Bond.\n\nThe entrance to Objekt 825 was positioned within a narrow inlet in Balaklava Bay, making it harder to observe from the open sea. In the event of a nuclear strike, this entrance channel could be sealed by blast doors seven metres high, ten metres wide, and two metres thick.\n\nThe complex was designed to remain standing – and sealed – even after a 100-kiloton nuclear explosion. For context, that's over six times the explosive yield of the bomb dropped on Hiroshima. If this happened, the base could become a fallout shelter for up to 3,000 people.\n\nPerhaps with this use in mind, Objekt 825 was fitted out with its own air and fuel supplies, allowing it to function independently. Heavy-duty diesel generators could keep things moving if mains power was cut off, and there were even underground railway lines. A smaller base, Objekt 820, was introduced within the complex to store torpedoes and nuclear weapons.\n\nThe 10,000-square-metres of Objekt 825 were made up of interconnected chambers and tunnels. This space included a dry dock, repair shops, and a reserve command post, as well as offices, accommodation and personnel facilities. There was even a bakery and hospital.\n\nWith a length of 602 metres (1,975 feet), the central channel could accommodate up to seven Black Sea Fleet submarines.\n\nThese submarines were the Soviets' Project 613 and Project 633 vessels, known as the Whiskey and Romeo classes. Based on the German Type XXI U-boat, 613s were propelled by diesel engines and electric motors, with a length of 76 metres, or 249 feet. Coming a few years later, the design for 633 was pretty much the same length, but with improved sonar and radio, and the ability to carry 14 torpedoes, rather than 12.\n\nThe Soviets didn't actually make many of these, as the diesel-hungry 633 was quickly superseded by nuclear-powered submarines. But as an interesting side note, the design was also licensed to China, which made far more of them, and reportedly still uses them today for training and static defence.\n\nBut back to Objekt 825.\n\nThe complex was extensive, but it wasn't unique. Each fleet within the Soviet Navy had its own base, meaning there were others for Russia's Northern, Baltic, and Pacific fleets. Reports released by the CIA also show that before 1958, the Soviet Air Force also built a number of underground bunkers as command posts for air defence.\n\nThe base was pretty much completed in 1961, and from that time it was used to store, maintain and repair the Black Sea Fleet's submarines. Between 170 and 230 personnel were based there, working at the dock and within engineering roles. Another 50 were employed to guard the base at all times.\n\nSecrecy remained paramount. Only one submarine was permitted to enter or exit the station at a time, and only at night. Employees could travel to their specific work area but nowhere else, with different access zones painted in different colours.\n\nAs Dmitrievich says, \"When asked: 'Where do you work?' – each employee, even at home – had to answer: 'I don't know.'\"\n\n## Retirement?\n\nThe base continued in operation for over three decades, but its strategic value gradually declined. The Soviet economy had been sagging for years, burdened in part by military overspending. As the 1980s closed out, Communist regimes in Eastern Europe began to fall like dominoes – the biggest of which was the Berlin Wall, in 1989.\n\nIn the early 1990s, the Cold War finally thawed forever. With the dissolution of the Soviet Union in 1991, Crimea became part of newly independent Ukraine, and the Black Sea Fleet was essentially divided between Ukraine and Russia. Rather than being a naval stronghold, the area became a contested space.\n\nTwo years later, in 1993, Objekt 825 was closed and largely abandoned. The exiting Russians removed its equipment, and looters carried off the rest. Pipe work, cables, tanks and metal slowly made their way out of the base and into the local economy. The last Soviet submarine left Balaklava Bay in 1996. In 2000, the facility finally came under the protection of Ukraine's naval forces.\n\nBecause it wasn't needed as an active site, the Ukrainian Ministry of Defence instead opened Objekt 825 as a naval museum, with its first visitors arriving in 2003. Fifty years after its inception, the veil was finally dropped from this top-secret location. For the first time ever, members of the public could see it for themselves.\n\nBut that's not the end of the story – and if it were, we probably wouldn't be talking about it today.\n\nAfter just over ten years of operation as a museum, it was all change – again – for Objekt 825. In 2014, Russia annexed Crimea, meaning that Balaklava again fell under its jurisdiction. Now known as Balaklava Underground Museum, Objekt 825 became a branch of Russia's Military History Museum of Fortifications.\n\nStill, the visitors came. As one TripAdvisor reviewer – based in Russia – commented in 2024, \"Where else can you pass under a real submarine hanging in the air in a special anti-nuclear facility over a hundred meters deep…\"\n\nTo the outside world, it seems that this is still very much a museum. But there are whispers that something else, rather less historic, is also going on there.\n\n## Signs of Reactivation\n\nSo far we've been dealing with the things we know. Well, as much as we can know anything about a once-secret location, controlled by a notoriously secretive state. From here, we'll be straying into the far murkier realms of conjecture and supposition. We can guess at a lot of things, but probing into the present-day use of Objekt 825 raises a lot more questions than it answers.\n\nLet's briefly return to the central question we posed at the start. Is Russia reactivating this underground base?\n\nThere's only a small amount of evidence we can probe here, but some evidence does exist.\n\nIn February this year, the Crimean Tatar group Atesh shared a video on the social media app Telegram. This video seemed to show two floating barriers at the entrance to Balaklava's harbour. The caption (translated into English) read:\n\n> \"The [Russian] occupiers are again using an old underground submarine base, which previously functioned as a museum, for military purposes. The facility, known as Object 825 GTS, is located in Balaclava and is an underground complex capable of sheltering submarines and providing repair and maintenance.\"\n\nClearly, there's no need to safeguard a museum site with barriers of this kind – they're far more likely to be used to protect valuable assets from Ukrainian naval and aerial drones.\n\nBut if this is true, and Russia really is reusing the base, it's unlikely to be for submarines. Because Objekt 825 existed as a museum for so long, we already know quite a bit about what it looks like. Or rather, we know what was there before.\n\nWhile Objekt 825 was designed to perfectly accommodate the Soviets' Whiskey and Romeo class subs, the Black Sea Fleet's present-day Kilo-class vessels are far broader in beam. They simply wouldn't fit in the 1960s-era setup.\n\nInstead, John CK Daly – a defence expert at The Jamestown Foundation – has put forward a theory that the Russian Navy might be using the base for its smaller surface ships. In the last few years, Ukrainian forces have inflicted serious damage on the Black Sea Fleet, striking key vessels such as the flagship missile cruiser Moskva, which sank to the depths back in April 2022.\n\nUkraine has also targeted enemy submarines in dry dock, forcing the Russian Navy to move them from Sevastopol to the secondary base of Novorossiisk.\n\nDaly suggests that Objekt 825 is likely to be renovated to allow it to welcome larger ships for shelter, saying:\n\n> \"The closure of the Turkish Straits, a consequence of Russian President Vladimir Putin's war, has severed the link between the Mediterranean squadron and the Black Sea Fleet, leaving Russia's warships isolated and vulnerable to Ukrainian attack. As Russia is determined to hold Crimea and has been reinforcing the peninsula's defenses, reworking Balaklava makes sense, as its size restrictions presently render it unsuitable for its original purpose.\"\n\nBut this isn't the first time rumours of the site's reopening have surfaced. In October 2022, Balaklava Bay was reportedly being redeveloped as a satellite naval facility for warships or the larger class of submarines. Images were shared that seemed to show construction work beginning, with floating cranes, barges and pilings in the bay.\n\nAlthough this could be explained away as additional yacht moorings, some commentators pointed to the creation of a new quay for warships.\n\nAccording to Naval News, writing in 2022, \"the timing and context clearly point to this being a new naval facility.\"\n\nAlongside this, it was thought that work had extended to Objekt 825 itself, with an entry passage being restored. At that point, it was thought that the base would be used to hide submarines carrying Russian Kalibr missiles from the eyes of Ukrainian anti-ship missiles.\n\nWhat came of this, we can't be entirely sure, and that's the frustrating thing about this story. If Russian forces were reinforcing the bay's defences back in February 2025, it's possible that the work begun in 2022 is still ongoing in some form. On the other hand, perhaps this is an entirely new project to bring Objekt 825 back into use.\n\n## Conclusion\n\nThe most plausible answer is that this subterranean hideout will be repurposed for protected storage and repairs, and as shelter for small surface craft and USVs: unscrewed, or unmanned, surface vessels. Essentially, explosive-carrying drone boats. In this sense, we can think of it as a ready-made fortified facility, with all the defensive weight that comes with being based underground.\n\nWhile Objekt 825's design and location were enormously useful in launching and shielding Cold War submarines, modern weapons like USVs have changed the face of warfare. Now, with Sevastopol being heavily targeted by Ukraine, Balaklava Bay and Objekt 825 could be stepped up as a less exposed and more drone-resistant base. Its tight, defensible nooks and crannies would be ideal for launching or hiding fast-attack boats, mine-layers, or drone swarms.\n\nOr perhaps this is all smoke and mirrors to an extent we haven't considered. As we're writing this in late-August 2025, Objekt 825 is still open as a museum. Tickets are available to buy online at 700 rubles for adults, 350 for children over seven. For this, you'll get an audio guide to narrate your way around the exhibits. So, if you're feeling brave enough, you could go along and see the site for yourself.\n\nUltimately, of course, we can't be sure. And maybe that's fitting for a location that was born in deep secrecy and devised to remain hidden. Seventy-five years on from the Soviet 1950s, the answer to what's happening at Objekt 825 must still be: \"I don't know.\"\n\n## Key Takeaways\n\n- Objekt 825, a secret Soviet submarine base in Crimea, was built in 1957 to hide submarines during the Cold War.\n- The base, now a museum, may be reactivated by Russia for modern military purposes, such as protecting small surface craft and drones.\n- Recent floating barriers at Balaklava's harbor suggest Russia is protecting valuable assets, potentially indicating the base's reactivation.\n- The base's strategic location in the Black Sea makes it significant for Russia's defense, especially amid current conflicts.\n- Construction and renovation activities around Balaklava Bay hint at ongoing efforts to repurpose Objekt 825 for contemporary military use.\n\n## Frequently Asked Questions\n\n### What is Objekt 825?\n\nObjekt 825 is a secret Soviet submarine base located beneath Mount Tavros in Balaklava, Crimea. It was built in 1957 to shelter Soviet submarines during the Cold War.\n\n### Why was Objekt 825 built in Balaklava?\n\nBalaklava was chosen for its strategic location and natural geography, which allowed for easy defense and disguise of the submarine base.\n\n### What types of submarines were housed in Objekt 825?\n\nThe base was designed to accommodate Soviet Project 613 (Whiskey class) and Project 633 (Romeo class) submarines.\n\n### How was Objekt 825 constructed?\n\nThe base was built underground by removing 120,000 tons of solid mountain rock and reinforcing the structure with concrete. The construction took eight years and was done in secret.\n\n### What happened to Objekt 825 after the Cold War?\n\nThe base was closed in 1993 and later turned into a naval museum, open to the public since 2003.\n\n### Is there evidence that Russia might be reactivating Objekt 825?\n\nIn February 2025, images showed two new floating barriers at the entrance to Balaklava's harbor, suggesting possible military use.\n\n### What is the current status of Objekt 825?\n\nAs of late-August 2025, Objekt 825 is still open as a museum, with tickets available for purchase.\n\n### What is the strategic importance of Balaklava and Objekt 825?\n\nBalaklava's location on the Crimean Peninsula makes it a strategic hub linking Europe with Asia, and Objekt 825 provides a hidden, defensible base for naval operations.\n\n### What is the theory about Russia's potential use of Objekt 825?\n\nDefense expert John CK Daly suggests that Russia might be using the base for smaller surface ships or unmanned surface vessels (USVs) due to the base's size restrictions for modern submarines.\n\n### How was the secrecy of Objekt 825 maintained during its construction?\n\nThe construction was carried out in secret, with the site classified as a closed city. Photography was banned, and strict security measures were implemented to prevent unauthorized access.\n\n## Sources\n\n- [Original MegaProjects video: Russia Might Be Reactivating a Secret Soviet Submarine Base](https://www.youtube.com/watch?v=mqcHm5xYe7A)\n\n## Related Coverage" url: https://megaprojects.pub/article/russia-reactivating-secret-soviet-submarine-base.md canonical: https://megaprojects.pub/article/russia-reactivating-secret-soviet-submarine-base datePublished: 2026-06-25 dateModified: 2026-06-25 author: - name: Simon Whistler url: https://megaprojects.pub/author/simon-whistler publisher: MegaProjects image: "https://media.megaprojects.pub/cdn-cgi/image/width=600,height=338,fit=cover,quality=80,format=auto/articles/mqcHm5xYe7A/hero.jpg" type: NewsArticle contentHash: 7200fb7d817efb2756d81b25b274e40c59052773f59a4b54f2aa1d18586519c0 tokens: 5302 summaryUrl: https://megaprojects.pub/article/russia-reactivating-secret-soviet-submarine-base.md.summary.md --- From above, you wouldn't spot the entrance to Objekt 825. In fact, you wouldn't know it was there at all. Flying over the town of Balaklava, in Crimea, you might look down on Mount Tavros, the sloping Baydar Valley, a pretty bay lined with pontoons. You'd never know that sprawled beneath the mountain is a top-secret submarine base. And of course, that's just how the Soviets intended it. First opened in 1957, Objekt 825 was born from deep Cold War tensions – hewn from the mountain rock to shelter Soviet submarines. Now mothballed, it's become a museum, where paying visitors walk its tunnels with passing interest. A fascinating relic of the past, you might think. But Objekt 825 might not be the remnant it appears. Because if its position in the Black Sea carried strategic weight during the Cold War, it's no less significant now. A handy hideaway on Ukraine's south coast, right when Russia is struggling to protect its Black Sea fleet. And there are distinct rumblings that far from being forgotten, this former submarine base is about to be awoken. In February 2025, images emerged showing two new floating barriers at the entrance to the harbour. Barriers that would only exist if the Russian state had something in there that it desperately wanted to protect. If this is true, Objekt 825 could be making an unexpected comeback. ## A Strategic Hub Today, Balaklava and Objekt 825 sit within occupied Ukraine, on the Crimean Peninsula. This area was annexed by Russia in 2014, but it's been a fiercely fought-over area for centuries. Linking Europe with Asia, and within easy reach of Africa and the Mediterranean, it's the centre of a strategic spider's web. We don't need a full history lesson here, but to give an idea of the political landscape, in the last century alone Crimea has been controlled by the Romanovs, Tatars and Nazis, as well as the Soviet Union, Ukraine, and the present-day Russian Federation. For generations beyond this, the port of Balaklava has been a waypoint for both civil and military maritime traffic. It's small wonder, then, that as the world's superpowers stood among the lingering wreckage of World War Two, and the Cold War began to ramp up, this coastal spot was chosen as the perfect location for a new submarine base. Plans for what was codenamed "Objekt 825 GTS" were first created way back in 1947, when it was nothing more than an idea. At this time, sensitive to the risk the Cold War posed, Soviet leader Joseph Stalin entrusted officer Lavrentiy Beria with a special task: find the best possible site for a submarine maintenance complex. Ideally, somewhere hidden away, but conveniently located for the launch of a retaliatory attack. Beria's search took years, but finally, in 1953, he locked on to the ideal location. The natural geography of Balaklava Bay meant that its narrow, winding inlet, with steep hillsides, could be easily defended and disguised. This was a base at which submarines could both survive an attack, and launch one of their own. By this time, Stalin had died and in the turmoil that followed, the Cold War was entering a new low. Both the United States and the Soviet Union were already growing their nuclear arsenal. On top of this, the Soviets began heavily investing in expanding their naval forces. Yet the cataclysmic fallout of Hiroshima and Nagasaki, almost a decade earlier, had proven just how devastating a nuclear bombing could be. If such an event took place over Balaklava, its natural route into the ocean highway would be blocked. Expensive submarines could be lost. It would be a major blow to the Soviets' Black Sea Fleet. In a nutshell, if someone did get wind of where they were, the Soviet submarines would be sitting ducks. The natural solution? Hide them. Building the entire facility underground would not only thwart any pesky spy satellites. It would also allow submarines to enter and exit Objekt 825 while completely submerged, making them almost invisible. The tell-tale exit hole, leading out to sea on the mountain's northern side, could be masked with camouflaged netting. ## Hidden in Plain Sight As you'd expect, it's not easy to hide an entire military base beneath a mountain. Building Objekt 825 was quite the endeavour. Overnight, the sleepy town of Balaklava became a construction zone, flooded with workers and engineers. This meant major upheaval for Balaklava's residents. But in the outside world, nobody knew it was going on at all. Because yes, if the build itself wasn't challenging enough, the whole operation had to be carried out in secret. The site was immediately classified, becoming a closed city and eventually vanishing from maps for the next fifty years. Obviously, this wasn't openly talked about – at least, not beyond the barbed wire fence. The only sign that something serious had shifted was a sudden and stringent tightening of security around the town. Photography was banned, and along with camouflaged observation towers, checkpoints popped up to detain would-be visitors. If you were caught trying to stroll into Balaklava, you'd better have a good reason. Even the residents were all-but locked down, with restrictions extending to their friends and family. Never mind if your Auntie Maria lived in Balaklava, you wouldn't be popping along for an impromptu cup of tea – or a samovar – any time soon. At least, not unless you had the reams of paperwork needed for a short-term visit. With this circle of secrecy pulled tight around the town, construction on Objekt 825 began. A special unit – numbered 528 – was formed to oversee the creation of the underground sub base. Drawing together engineers and personnel from the Black Sea Fleet, 528 was responsible for the ambitious excavation and construction work. But the notion of subterranean builds definitely wasn't new to the Soviet government. In the closed city of Sevastopol alone, a veritable rabbits' warren of underground structures and catacombs had been in place for decades. In 'Declassified Crimea', Khorsun Dmitrievich writes that the area beneath Sevastopol is estimated to encompass between 315,000 and 350,000 square kilometres. This includes, "more than 600 bunkers, of which only about half are statistically registered. About 100 underground structures belong to the Black Sea Fleet". Across Russia, hundreds of kilometres of nuclear-proof tunnels were ready and waiting. Yet building these structures was deeply labour-intensive. Construction on Objekt 825 alone took eight years of backbreaking work. It's said that underground work cost 67 million Soviet rubles, with equipment and life support systems adding another 65 million rubles to that figure. Creating the space they needed involved removing an incredible 120,000 tons of solid mountain to make way for a vast subterranean network of chambers and tunnels. This could only be done by successive drilling and blasting, using a similar method to hard rock mining. Workers would drill deep shafts in the rock, before packing them with explosives and, we hope, retreating to a safe distance. The resulting void could then be cleared of its rubble and a concrete formwork built to reinforce the structure. To preserve secrecy, supplies arrived – and rock was cleared out and dumped – under cover of darkness. A hidden lair inside a mountain, with barges silently stealing in at night? It's all wonderfully James Bond. The entrance to Objekt 825 was positioned within a narrow inlet in Balaklava Bay, making it harder to observe from the open sea. In the event of a nuclear strike, this entrance channel could be sealed by blast doors seven metres high, ten metres wide, and two metres thick. The complex was designed to remain standing – and sealed – even after a 100-kiloton nuclear explosion. For context, that's over six times the explosive yield of the bomb dropped on Hiroshima. If this happened, the base could become a fallout shelter for up to 3,000 people. Perhaps with this use in mind, Objekt 825 was fitted out with its own air and fuel supplies, allowing it to function independently. Heavy-duty diesel generators could keep things moving if mains power was cut off, and there were even underground railway lines. A smaller base, Objekt 820, was introduced within the complex to store torpedoes and nuclear weapons. The 10,000-square-metres of Objekt 825 were made up of interconnected chambers and tunnels. This space included a dry dock, repair shops, and a reserve command post, as well as offices, accommodation and personnel facilities. There was even a bakery and hospital. With a length of 602 metres (1,975 feet), the central channel could accommodate up to seven Black Sea Fleet submarines. These submarines were the Soviets' Project 613 and Project 633 vessels, known as the Whiskey and Romeo classes. Based on the German Type XXI U-boat, 613s were propelled by diesel engines and electric motors, with a length of 76 metres, or 249 feet. Coming a few years later, the design for 633 was pretty much the same length, but with improved sonar and radio, and the ability to carry 14 torpedoes, rather than 12. The Soviets didn't actually make many of these, as the diesel-hungry 633 was quickly superseded by nuclear-powered submarines. But as an interesting side note, the design was also licensed to China, which made far more of them, and reportedly still uses them today for training and static defence. But back to Objekt 825. The complex was extensive, but it wasn't unique. Each fleet within the Soviet Navy had its own base, meaning there were others for Russia's Northern, Baltic, and Pacific fleets. Reports released by the CIA also show that before 1958, the Soviet Air Force also built a number of underground bunkers as command posts for air defence. The base was pretty much completed in 1961, and from that time it was used to store, maintain and repair the Black Sea Fleet's submarines. Between 170 and 230 personnel were based there, working at the dock and within engineering roles. Another 50 were employed to guard the base at all times. Secrecy remained paramount. Only one submarine was permitted to enter or exit the station at a time, and only at night. Employees could travel to their specific work area but nowhere else, with different access zones painted in different colours. As Dmitrievich says, "When asked: 'Where do you work?' – each employee, even at home – had to answer: 'I don't know.'" ## Retirement? The base continued in operation for over three decades, but its strategic value gradually declined. The Soviet economy had been sagging for years, burdened in part by military overspending. As the 1980s closed out, Communist regimes in Eastern Europe began to fall like dominoes – the biggest of which was the Berlin Wall, in 1989. In the early 1990s, the Cold War finally thawed forever. With the dissolution of the Soviet Union in 1991, Crimea became part of newly independent Ukraine, and the Black Sea Fleet was essentially divided between Ukraine and Russia. Rather than being a naval stronghold, the area became a contested space. Two years later, in 1993, Objekt 825 was closed and largely abandoned. The exiting Russians removed its equipment, and looters carried off the rest. Pipe work, cables, tanks and metal slowly made their way out of the base and into the local economy. The last Soviet submarine left Balaklava Bay in 1996. In 2000, the facility finally came under the protection of Ukraine's naval forces. Because it wasn't needed as an active site, the Ukrainian Ministry of Defence instead opened Objekt 825 as a naval museum, with its first visitors arriving in 2003. Fifty years after its inception, the veil was finally dropped from this top-secret location. For the first time ever, members of the public could see it for themselves. But that's not the end of the story – and if it were, we probably wouldn't be talking about it today. After just over ten years of operation as a museum, it was all change – again – for Objekt 825. In 2014, Russia annexed Crimea, meaning that Balaklava again fell under its jurisdiction. Now known as Balaklava Underground Museum, Objekt 825 became a branch of Russia's Military History Museum of Fortifications. Still, the visitors came. As one TripAdvisor reviewer – based in Russia – commented in 2024, "Where else can you pass under a real submarine hanging in the air in a special anti-nuclear facility over a hundred meters deep…" To the outside world, it seems that this is still very much a museum. But there are whispers that something else, rather less historic, is also going on there. ## Signs of Reactivation So far we've been dealing with the things we know. Well, as much as we can know anything about a once-secret location, controlled by a notoriously secretive state. From here, we'll be straying into the far murkier realms of conjecture and supposition. We can guess at a lot of things, but probing into the present-day use of Objekt 825 raises a lot more questions than it answers. Let's briefly return to the central question we posed at the start. Is Russia reactivating this underground base? There's only a small amount of evidence we can probe here, but some evidence does exist. In February this year, the Crimean Tatar group Atesh shared a video on the social media app Telegram. This video seemed to show two floating barriers at the entrance to Balaklava's harbour. The caption (translated into English) read: > "The [Russian] occupiers are again using an old underground submarine base, which previously functioned as a museum, for military purposes. The facility, known as Object 825 GTS, is located in Balaclava and is an underground complex capable of sheltering submarines and providing repair and maintenance." Clearly, there's no need to safeguard a museum site with barriers of this kind – they're far more likely to be used to protect valuable assets from Ukrainian naval and aerial drones. But if this is true, and Russia really is reusing the base, it's unlikely to be for submarines. Because Objekt 825 existed as a museum for so long, we already know quite a bit about what it looks like. Or rather, we know what was there before. While Objekt 825 was designed to perfectly accommodate the Soviets' Whiskey and Romeo class subs, the Black Sea Fleet's present-day Kilo-class vessels are far broader in beam. They simply wouldn't fit in the 1960s-era setup. Instead, John CK Daly – a defence expert at The Jamestown Foundation – has put forward a theory that the Russian Navy might be using the base for its smaller surface ships. In the last few years, Ukrainian forces have inflicted serious damage on the Black Sea Fleet, striking key vessels such as the flagship missile cruiser Moskva, which sank to the depths back in April 2022. Ukraine has also targeted enemy submarines in dry dock, forcing the Russian Navy to move them from Sevastopol to the secondary base of Novorossiisk. Daly suggests that Objekt 825 is likely to be renovated to allow it to welcome larger ships for shelter, saying: > "The closure of the Turkish Straits, a consequence of Russian President Vladimir Putin's war, has severed the link between the Mediterranean squadron and the Black Sea Fleet, leaving Russia's warships isolated and vulnerable to Ukrainian attack. As Russia is determined to hold Crimea and has been reinforcing the peninsula's defenses, reworking Balaklava makes sense, as its size restrictions presently render it unsuitable for its original purpose." But this isn't the first time rumours of the site's reopening have surfaced. In October 2022, Balaklava Bay was reportedly being redeveloped as a satellite naval facility for warships or the larger class of submarines. Images were shared that seemed to show construction work beginning, with floating cranes, barges and pilings in the bay. Although this could be explained away as additional yacht moorings, some commentators pointed to the creation of a new quay for warships. According to Naval News, writing in 2022, "the timing and context clearly point to this being a new naval facility." Alongside this, it was thought that work had extended to Objekt 825 itself, with an entry passage being restored. At that point, it was thought that the base would be used to hide submarines carrying Russian Kalibr missiles from the eyes of Ukrainian anti-ship missiles. What came of this, we can't be entirely sure, and that's the frustrating thing about this story. If Russian forces were reinforcing the bay's defences back in February 2025, it's possible that the work begun in 2022 is still ongoing in some form. On the other hand, perhaps this is an entirely new project to bring Objekt 825 back into use. ## Conclusion The most plausible answer is that this subterranean hideout will be repurposed for protected storage and repairs, and as shelter for small surface craft and USVs: unscrewed, or unmanned, surface vessels. Essentially, explosive-carrying drone boats. In this sense, we can think of it as a ready-made fortified facility, with all the defensive weight that comes with being based underground. While Objekt 825's design and location were enormously useful in launching and shielding Cold War submarines, modern weapons like USVs have changed the face of warfare. Now, with Sevastopol being heavily targeted by Ukraine, Balaklava Bay and Objekt 825 could be stepped up as a less exposed and more drone-resistant base. Its tight, defensible nooks and crannies would be ideal for launching or hiding fast-attack boats, mine-layers, or drone swarms. Or perhaps this is all smoke and mirrors to an extent we haven't considered. As we're writing this in late-August 2025, Objekt 825 is still open as a museum. Tickets are available to buy online at 700 rubles for adults, 350 for children over seven. For this, you'll get an audio guide to narrate your way around the exhibits. So, if you're feeling brave enough, you could go along and see the site for yourself. Ultimately, of course, we can't be sure. And maybe that's fitting for a location that was born in deep secrecy and devised to remain hidden. Seventy-five years on from the Soviet 1950s, the answer to what's happening at Objekt 825 must still be: "I don't know." ## Key Takeaways - Objekt 825, a secret Soviet submarine base in Crimea, was built in 1957 to hide submarines during the Cold War. - The base, now a museum, may be reactivated by Russia for modern military purposes, such as protecting small surface craft and drones. - Recent floating barriers at Balaklava's harbor suggest Russia is protecting valuable assets, potentially indicating the base's reactivation. - The base's strategic location in the Black Sea makes it significant for Russia's defense, especially amid current conflicts. - Construction and renovation activities around Balaklava Bay hint at ongoing efforts to repurpose Objekt 825 for contemporary military use. ## Frequently Asked Questions ### What is Objekt 825? Objekt 825 is a secret Soviet submarine base located beneath Mount Tavros in Balaklava, Crimea. It was built in 1957 to shelter Soviet submarines during the Cold War. ### Why was Objekt 825 built in Balaklava? Balaklava was chosen for its strategic location and natural geography, which allowed for easy defense and disguise of the submarine base. ### What types of submarines were housed in Objekt 825? The base was designed to accommodate Soviet Project 613 (Whiskey class) and Project 633 (Romeo class) submarines. ### How was Objekt 825 constructed? The base was built underground by removing 120,000 tons of solid mountain rock and reinforcing the structure with concrete. The construction took eight years and was done in secret. ### What happened to Objekt 825 after the Cold War? The base was closed in 1993 and later turned into a naval museum, open to the public since 2003. ### Is there evidence that Russia might be reactivating Objekt 825? In February 2025, images showed two new floating barriers at the entrance to Balaklava's harbor, suggesting possible military use. ### What is the current status of Objekt 825? As of late-August 2025, Objekt 825 is still open as a museum, with tickets available for purchase. ### What is the strategic importance of Balaklava and Objekt 825? Balaklava's location on the Crimean Peninsula makes it a strategic hub linking Europe with Asia, and Objekt 825 provides a hidden, defensible base for naval operations. ### What is the theory about Russia's potential use of Objekt 825? Defense expert John CK Daly suggests that Russia might be using the base for smaller surface ships or unmanned surface vessels (USVs) due to the base's size restrictions for modern submarines. ### How was the secrecy of Objekt 825 maintained during its construction? The construction was carried out in secret, with the site classified as a closed city. Photography was banned, and strict security measures were implemented to prevent unauthorized access. ## Sources - [Original MegaProjects video: Russia Might Be Reactivating a Secret Soviet Submarine Base](https://www.youtube.com/watch?v=mqcHm5xYe7A) ## Related Coverage