USS Squalus (SS-192), a diesel-electric submarine built at the Portsmouth Navy Yard, Portsmouth, New Hampshire and commissioned there on 1 March 1939, suffered a catastrophic valve failure during a test dive off the Isle of Shoals at 0740 on 23 May. Partially flooded, the submarine sank to the bottom and came to rest keel down in 40 fathoms (240 feet) of water. Navy divers and salvage ships responded quickly, and the following day began operations to rescue the surviving 32 crew members and one civilian from the forward sections of the boat.
