The submarine was found by the Lost 52 Project, which locates lost U.S. World War II submarines, and is the first U.S. submarine discovered off the coast of Japan. Japanese records indicate that the sub was sunk by a 500-pound bomb dropped by a naval bomber in February 1944.
HMS Urge—part of Britain's 10th Submarine Flotilla—left the Mediterranean island of Malta on April 27, 1942 but never made it to its destination of the Egyptian port of Alexandria. Until its discovery this summer, the reason for both the ship's disappearance and its final resting place were unknown. The discovery of HMS Urge suggests it sank in 1942 after hitting an explosive marine mine placed by an enemy German warship.
A team led by Genoa-based diver wreck-hunter, Massimo Domenico Bordone, found the remains of the British submarine at about 100 metres deep, about 5 nautical miles east of the isle of Tavolara, off Sardinia.
The wreckage is reportedly in quite a good condition with only its prow showing damage from the explosion. In all likelihood, experts say the vessel's inner chamber was not flooded as it sank
HMS Tarpon left Portsmouth on 5 April 1940 and ordered to Norway. On the 10th Tarpon was ordered to take up a new position but was never heard from again. Post War German records showed that Tarpon had attacked the Q-ship Schiff 40/Schürbek, but her first torpedoes had missed. A sustained counterattack that went on most of the morning finally brought wreckage to the surface and it became clear the submarine had been sunk.
The 400-ton Russian submarine, commissioned in 1911, was the biggest in the pre-revolutionary Russian navy. During the first world war, she served in the Baltic Fleet making 16 patrols and unsuccessfully attacked the German coastal defence ship SMS Beowulf.
In November 1915 during her 17th patrol, she struck a mine and sank near Hiiumaa with the loss of all 35 seamen and came to rest at a depth of about 30 meters.