USS Indianapolis (CL/CA-35) was a heavy cruiser of the United States Navy, named for the city of Indianapolis, Indiana. Launched in 1931, it was the flagship for the commander of Scouting Force 1 for eight years, then flagship for Admiral Raymond Spruance in 1943 and 1944 while he commanded the Fifth Fleet in battles across the Central Pacific during World War II. In July 1945, Indianapolis completed a top-secret high-speed trip to deliver uranium and other components for "Little Boy", the first nuclear weapon ever used in combat, to the Tinian Naval Base, and subsequently departed for the Philippines on training duty. At 0015 on 30 July, the ship was torpedoed by the Imperial Japanese Navy submarine , and sank in 12 minutes. Of 1,195 crewmen aboard, approximately 300 went down with the ship. The remaining 890 faced exposure, dehydration, saltwater poisoning, and shark attacks while stranded in the open ocean with few lifeboats and almost no food or water. The Navy only learned of the sinking four days later, when survivors were spotted by the crew of a PV-1 Ventura on routine patrol. A US Navy PBY seaplane crew landed to save those in the water. Only 316 survived. The sinking of Indianapolis resulted in the greatest loss of life at sea from a single ship in the history of the US Navy. On 19 August 2017, a search team financed by Microsoft co-founder Paul Allen located the wreckage in the Philippine Sea lying at a depth of approximately . On 20 December, 2018, the crew of Indianapolis was collectively awarded a Congressional Gold Medal. Construction Indianapolis was the second of two ships in the Portland class, the third class of "treaty cruisers" constructed by the United States Navy following the Washington Naval Treaty of 1922, after the two vessels of the , ordered in 1926, and the six of the , ordered in 1927. Ordered for the US Navy in fiscal year 1930, Indianapolis was originally designated as a light cruiser because of her thin armor and given the hull classification symbol CL-35. She was reclassified a heavy cruiser, because of her guns, with the symbol CA-35 on 1 July 1931, in accordance with the London Naval Treaty. As built, the Portland-class cruisers were designed for a standard displacement of , and a full-load displacement of . However, when completed, Indianapolis did not reach this weight, displacing .