In 1953, Joseph Stalin signed the plans for a top-secret nuclear submarine base that would become the operational home for the fearsome Soviet Black Sea Fleet.

Hidden inside the base of a mountain in the port town of Balaklava on Ukraine’s Crimean coast, the 153,000 square-foot facility took nine years to build and its entrance camouflaged from spy planes. It could survive a direct nuclear hit and at maximum capacity could hold 3,000 people with supplies to sustain them for a month. Best of all, the vast subs that slunk in and out of here between tours of duty could enter and leave underwater, keeping them from prying eyes at all times.

Once the most sensitive and secretive of Soviet Cold War hotspots, today it is preserved as a museum. I manage to get special permission to drive into the base during the 8,000-mile Land Rover Journey of Discovery expedition to Beijing. We were the first to do so since the Soviet trucks and trailers that ferried in missiles, supplies and essentials over its 40 years of operation.

Driving through the cavernous entrance carved into the heavy rock of the mountain was pure James Bond, but the base that unfolded inside was a hard-hitting mix of superspy fantasy and the coarse reality of the Cold War world in which it played a key part.

The local guide explained how the facility was split into two clear sections on either side of the huge submarine channel that ran through the center, one side used for the operational running of the base and the other for arming the nuclear warheads. Then she dropped a bombshell of her own.

She had worked on the operational side of the base for five years with level-two security clearance — just one step below the highest possible — yet in all her time at the facility she had never known the nuclear side existed. She was only made aware of it when she began guiding tours here years later.

As she puts it: “It was in our culture then not to ask about what didn’t concern us. A common saying at the time was, ‘The less you know, the better you sleep.’”

Not only was this place so secretive that even its own employees were kept in the dark, every possible measure was taken to keep its existence unknown to the outside world. This included removing Balaklava from all maps in 1957 (it would be 1992 before it reared its head again) and employees’ family members from neighboring Sevastopol — itself a closed city that needed heavy security clearance to access — were put through extensive vetting before visits to loved ones were allowed.

Inside the base we first toured the operational side, working our way through the broad network of tunnels until we came to the dry dock, so large that it was capable of holding a 300-foot submarine.

Beside the dry dock was the huge submarine channel, with space for six such subs end to end. Curved to deflect any blast inside the base, the channel is lined with steel gangways above head height. It provides a fearsome environment, with a hulking sub sitting in the black water and the loud echoes of urgent footfalls, the clanking of tools, and the humming of generators.

Crossing to the other side of the base became even more interesting. Here even the tunnels making up the connecting network were curved for blast protection, as this was where the missiles were armed.

We saw the cabinet where the radioactive parts of the weapons were stored. Now empty, its massive steel roller door sits ajar just as it was left when the lethal payload it once concealed was taken by Soviet authorities.

Even the tunnels making up the connecting network were curved for blast protection.

Finally, we came to the epicenter of this underground lair, the room that stored the armed missiles. It looks innocuous now, but to imagine this place primed with as many as 50 nuclear devices left a sobering scent in the air.

As a final unusual touch, our guide pointed out a simple-looking plastic mount, similar to a small patio light, attached to the wall of the room and holding a solitary human hair. This most basic of devices monitored the humidity in the room, which had to be critically maintained at 60 percent — deviation either way could have resulted in an explosion large enough to destroy the entire base, not to mention the mountain that housed it and much of the surrounding area. If the hair began bending, that was the engineers’ cue to adjust the ventilation, and quickly.

Rolling back out into the sunlight of Balaklava’s bay was almost as odd as driving in had been, but for quite different reasons.

Now instead of Cold War killers, the bay is home to a glittering array of yachts from all over the world and at the water’s edge instead of subs skulking in and out, throngs of locals indulged in a spot of fishing while shooting the breeze over a couple of beers.

If that isn’t a sign of progress, we don’t know what is.

Photos: Anthony Cullen/Incword.com