How Tough Were U.S. Submarines? Darn Tough!!
USS Salmon (SS-182) was designed in February 1935, nearly seven years before World War II started. Her test depth was only 250 feet, little more than half of Razorback's.
On the night of 30 October, 1944 (just a few weeks after the above photo was taken), Salmon was depth charged by three Japanese escorts. The first two patterns exploded very close to the submerged submarine, which was already operating beyond her test depth at a depth of 310 feet.
Damage from the attack was so severe that before Salmon could be brought under control, she reached an estimated depth of 620 feet, more than twice her test depth! (The exact depth is unknown because every depth gauge in the submarine had been shattered in the attack). The water pressure was so great that her pressure hull was deformed between frames.
Salmon's crew was able to bring her safely back to the surface and escape from Japanese controlled waters. After temporary repairs, she was sent stateside, where it was determined that she was damaged beyond economical repair and Salmon was decommissioned and scrapped as a war loss.
Source: The Fleet Submarine in the U.S. Navy, CDR John Alden, USN (ret), Naval Institute Press.
Official U.S. Navy Photograph courtesy of the Naval History and Heritage Command.