Wreckage of USS Indianapolis discovered
Wreckage of USS Indianapolis discovered U.S. Naval History and Heritage Command/U.S. Navy/Handout/Reuters

As many as 72 years after the end of World War II, a team of civilian researchers has discovered the hulk of USS Indianapolis, the Portland-class heavy cruiser which was torpedoed by a Japanese submarine, leading to the greatest maritime loss in the history of the US Navy.

The doomed cruiser, which played a crucial part in the atomic bombing of Hiroshima, was discovered 18,000ft (5,500m) below the surface of the Philippine sea, according to Microsoft co-founder Paul Allen, who headed the 16-person expedition crew of Research Vessel (R/V) Petrel that made this discovery.

"To be able to honour the brave men of the USS Indianapolis and their families through the discovery of a ship that played such a significant role in ending World War II is truly humbling," Allen said in a statement. He also took to Twitter to share the update.

In the final days of World War II, Indianapolis completed a secret, high-speed trip and delivered parts for Little Boy, the first atomic bomb used by the US in Hiroshima. However, during its journey from Guam to the Philippines, the vessel suffered its tragic fate and was struck by the Imperial Japanese Navy submarine, I-58.

Indianapolis went down in just 12 minutes, making it impossible for the 1,196 crewmen aboard to send out a distress signal or call for help. Only 316 sailors and marines survived, with nearly 300 crewmen sinking with the ship and the rest (with fewer life-jackets) succumbing to shark attacks, saltwater poisoning and dehydration. Only 22 of the survivors are alive today.

"As Americans, we all owe a debt of gratitude to the crew for their courage, persistence, and sacrifice in the face of horrendous circumstances," Allen said. "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 and his crew will continue to survey the site of discovery and follow up with a live tour of the wreckage as per relevant rules of the US Navy. The Microsoft co-founder got to this discovery after acquiring and retrofitting the 250-foot R/V Petrel with state-of-the-art subsea equipment to make it capable of diving up to 6,000 metres.

"The Petrel and its capabilities, the technology it has and the research we've done, are the culmination of years of dedication and hard work," said Robert Kraft, director of subsea operations for Allen. "We've assembled and integrated this technology, assets and unique capability into an operating platform which is now one among very few on the planet."

Before this, Allen's crew had also unearthed the remains of Japanese battleship Musashi (March 2015) and World War II destroyer Artigliere (March 2017).