Ocean researchers say they’ve found the deepest naval shipwreck ever discovered, about four miles underwater, and they believe it is a U.S. Navy destroyer from World War II. Vulcan Inc., founded by the late Microsoft billionaire Paul Allen, released video obtained from one of its research vessels showing scattered remains of the ship about 20,400 feet below sea level at the bottom of the Philippine Sea. “As with all their expeditions, the crew aboard Research Vessel Petrel hope this discovery will bring a sense of closure for the families of those lost during this battle,” the company said in a statement. Sky News reports that the ship is thought to be USS Johnston DD-557, a destroyer sunk during the Battle of Leyte Gulf off the coast of the Philippines on Oct. 25, 1944. It is considered to be one of the largest naval attacks in history, involving more than 200,000 naval personnel.