The Portland-class heavy cruiser USS Indianapolis underway in Pearl Harbor in 1937. The ship was sunk on July 30, 1945, by a Japanese submarine in the Philippine Sea following delivery of parts for the first atomic bomb used in combat to the U.S. air base at Tinian. Of 1,196 crewmen aboard, about 300 went down with the ship. The rest faced exposure, dehydration, saltwater poisoning and shark attacks while floating with few lifeboats and almost no food or water. The Navy learned of the sinking when survivors were spotted four days later by the crew of a PV-1 Ventura on routine patrol. Only 317 survived. Navy photo