The Indianapolis was sunk by a Japanese torpedo in the last days of World War Two after it had delivered components for the atomic bomb to be dropped on Hiroshima. Microsoft founder Paul Allen's team found the wreck.
A Japanese submarine fired on the USS Indianapolis during the night of July 30, 1945 when she was in shark-filled waters halfway between Guam and the Philippines.
The 610-foot (186 meter) cruiser sank in 12 minutes. While about 800 of the 1,196 crew survived the sinking, only 321 were still alive three and a half days later when a Navy seaplane on a routine patrol spotted the survivors.Only 317 crewmen survived the attack and its aftermath.
It was the US Navy's worst single at-sea loss of life.
Days earlier the Indianapolis had delivered the uranium and other components to the island of Tinian for the atomic bomb that was later dropped on Hiroshima. Because the mission was secret, she had sailed alone without the usual escort of ships which would have been better able to detect and fight off Japanese submarines.
There are 19 survivors from the USS Indianapolis still alive today, and the Navy plans to honor them and families of the ship's crew.
Different search area
Last year a Navy historian researched new information about the ship's last movements which indicated a different search area.
That led a team of civilian researchers headed by Microsoft co-founder Paul Allen to spend months searching 600 square miles (1,500 square kilometers) of ocean bed beneath the Philippine Sea. Allen announced the find on Friday via his website but did not disclose the precise location, following a request from the Navy.
"While our search for the rest of the wreckage will continue, I hope everyone connected to this historic ship will feel some measure of closure at this discovery so long in coming," Allen said.
Allen's Research Vessel Petrel is a 250-foot vessel equipped with state-of-the-art equipment capable of diving to 6,000 meters. It has a 13-person crew on board.
The USS Indianapolis' commanding officer, Rear Admiral Charles B. McVay III, was court-martialed for not sailing a zigzag course to evade submarines, but survivors believe he was made a scapegoat to detract from the Navy's own failings. While several SOS signals were sent before the cruiser sank, none were taken seriously and little was done when the ship failed to arrive at its destination on time. McVay committed suicide in 1968. Congress passed an act in 2000 clearing his name.