At 12:14 a.m. on July 30, 1945, the USS Indianapolis was torpedoed by a Japanese submarine in the Philippine Sea and sank in 12 minutes. Of 1,196 men on board, approximately 300 went down with the ship. The remainder, about 900 men, were left floating in shark-infested waters with no lifeboats and most with no food or water. The ship was never missed, and by the time the survivors were spotted by accident four days later only 316 men were still alive.
The Discovery Channel has an interesting site.Another is here.
The oral recollections of Captain Charles B. McVay, III, USN, Commanding Officer of USS Indianapolis