When U-260 got lost off the South Irish coast, about four miles from the picturesque village of Glandore, the war was winding down - it was 12 March 1945.
The VII C-class German submarine had been commissioned three years earlier. Its most notable actions had been as part of a "wolf pack" that, with four other U-boats, had sunk 14 ships in convoy ONS-154.
U-260 had left Kristiansand in Norway for operations in the English Channel in February. She was travelling underwater about 20 miles off Fastnet when her hull was rocked by an explosion, attributed to a contact or antenna mine.
Managing to surface, U-260 headed for shore. But after several hours she became unmanageable and her captain Klaus Becker, who was in radio contact with U-Boat Command, was ordered to scuttle his vessel.
The crew put to shore in rubber dinghies. The flood-tide swept them east, and many clambered up the rocky headland to the Galley Head lighthouse. Those who missed it were eventually picked up by the Courtmacsherry Lifeboat.
All 48 crew survived. The eldest was 23 and they spent the rest of the war in a military camp in Kildare.
In 1975 a fisherman, Colin Barnes, snagged his nets off Glandore and noted the position. Some ten years later his earlier suspicions of wreckage were confirmed when he made a pass over the area with a magnetometer.
Colin thought he had found the wreck of the cargo ship Counsellor, which had been sunk by a mine in 1917. His friend Joe Barry made an inspection dive and was surprised to land on the conning tower of a submarine.
Since then diver Nic Gotto, owner of Sundancer II, has visited the submarine regularly with diving tourists.
U-260 lies in 46m on a rocky bed. Diving conditions are usually excellent, with very good visibility despite the depth. The 66m submarine is almost on its beam ends, its port side on the rocks. It is intact except for its bow, which was blown off when the mine struck, revealing four torpedo tubes and severed hydrovanes.
One periscope is extended and still watertight after 52 years under water. A diver can peer through the Zeiss optics and observe various brass gears and prisms used to operate this masterpiece of engineering.
Some outer-hull plating has fallen off from decay, and the deck-planking no longer exists. The nose of a torpedo can be seen by looking through one of the four bow tubes, and a fifth tube is visible between the twin steel propellers in the stern. Its full length is best viewed by peering through the aft deck. Several dives are needed to fully savour this unusual wreck. And one particularly interesting sight lies on the port side of the conning tower, where a folded snorkel can be seen.
As early as 1933, Hellmuth Walter had suggested that submarines could run at full speed underwater on their diesel engines by introducing air from the atmosphere and expending exhaust gases through a vertical airmast, that could be raised or lowered as required. The U-boat could stay submerged, avoiding enemy detection.
The German Chief of Naval War Staff, Admiral Doenitz, was intrigued by Walter's idea and pledged support to develop it. Walter incorporated a ball or float in the head-valve at the highest point in the mast to prevent seawater entering in rough weather. The hull ofthe submarine would act as a great air cushion and the diesel engines could safely draw air for up to a minute from within.
The airmast became known as a Walter Snorkel and the first was made in June 1943.
U-260 had her snorkel fitted just before her eighth wartime cruise, in August 1944. It must have been folded away on her deck at the time of her destruction; no signs of decay are evident on it, so it must have been made from non-ferrous metal. Time has not dimmed the fascination in the "Glandore Sub", as the droves of visiting divers testify. Electric motors that once hummed as they warmed the crew are now silent and cold. Her cramped accommodation is tenanted by conger eels and blanketed in silt.
U-260's once-gleaming six-cylinder engines are entombed in perpetual darkness. And her snorkel and periscope remain as monuments to the genius of men like Walter and Zeiss.