On the 6th December 1941, after a distinguished service career, the British submarine HMS Perseus was cruising at the surface recharging her batteries, when with no warning, there was a devastating explosion. She had hit an Italian mine and plummeted to the seabed two miles south of the Greek island of Kefalonia.

There were 59 crew members and two passengers aboard, of which only one survived. John Capes, who was hitching a lift to Alexandria, wrote in letters (now preserved at the Gosport Royal Navy Submarine Museum) that the boat twisted, plunged, and hit the bottom with a “nerve-shattering jolt”. The door was forced shut by the pressure of water on the other side. “It was creaking under the great pressure. Jets and trickles from the rubber joint were seeping through.”

According to his account, Capes dragged three injured crew members to the escape hatch in the engine room where he was sleeping before fitting all of them with escape apparatus, which consisted of a rubber life jacket with an oxygen bottle. He then pushed his injured companions up through the hatch before taking a last swig of rum and exiting himself, the buoyancy of the jacket lifting him quickly to the surface. He arrived at the surface in the pitch dark, alone.

After a few moments of despair, he started the eight-hour swim towards the faintly visible cliffs of Kefalonia. It took 18 months to get him off the island before the dangerous 400mile journey back to the submarine service in Alexandria. John Capes spent the next 40 years defending his incredible story, despite a general disbelief by service personnel as well as the public.

In 1997, 12 years after Capes died, his story was finally verified by Kostas Thoctarides, who discovered the wreck exactly as he had described, including his empty torpedo tube bunk as well as his blitz bottle from which he had taken his final swig of rum.

The road to HMS Perseus

I had heard of the HMS Perseus along with seeing some grainy photographs of her towards the end of 2018, when Arnaud and I decided we were going to attempt to freedive her as soon as possible. In early 2019  read an amazing article about her, showing how intact she was, which helped us garner support for our expedition. We needed equipment, money – but more important – the right freedivers.

Sitting at -52m, the depth was not particularly tough; repeating the dive in less than perfect conditions would be more challenging, but still not beyond many of our members. The real difficulties would be locating the wreck and creating a stable platform to dive from, especially difficult in the open sea. Even anchoring at this depth is quite a technical trial.

Our yacht, Lito, was professionally manned by Panos and Elias, who had worked out the intricacies of anchoring in deep water whilst using the wind to align us with dive sites. They had recently acquired a Furuno echo sounder specifically for locating dive sites, which paid dividends on this trip. We had set a September expedition date and started to work through technical details when fortune shone on us again. On June 8^th a group of rebreather divers from BlueCycle and ALS Marine Consultants set about removing ghost nets from HMS Perseus. This would not only make our visit considerably more visually attractive but also significantly safer.

We visited the Royal Navy Submarine Museum and the HMS Alliance in Gosport as well as the escape tower used to train submariners how to escape a sunken vessel after such disasters as the Perseus. HMS Alliance was built shortly after the Perseus and is slightly longer at 85m (as opposed to 70m), but it gave us a good idea of the scale of the wreck.