A crew of deep-sea explorers and historians looking for lost World War II warships found a second Japanese aircraft carrier that went down in the historic Battle of Midway.Vulcan Inc director of undersea operations Rob Kraft said a review of sonar data captured on Sunday shows what could be either the Japanese carrier Akagi or the Soryu resting in nearly 5 490m of water in the Pacific Ocean more than 2 090km northwest of Pearl Harbor.Researchers used an autonomous underwater vehicle, or AUV, equipped with sonar to find the ship. The vehicle had been out overnight collecting data and the image of a warship appeared in the first set of readings Sunday morning.To confirm exactly which ship they've found the crew will deploy the AUV for another eight-hour mission where it will capture high-resolution sonar images of the site. The initial readings were captures using lower resolution sonar. The high resolution scans will allow the crew to measure the ship and confirm its identity.The find comes on the heels of the discovery of another Japanese carrier, the Kaga, last week.The crew of the research vessel Petrel is hoping to find and survey all lost ships from the 1942 Battle of Midway, which historians consider a pivotal fight for the US in the Pacific during WWII.The battle was fought between American and Japanese aircraft carriers and warplanes about 320km off Midway Atoll, a former military installation the Japanese hoped to capture in a surprise attack.The US, however, intercepted Japanese communications about the strike and were waiting when they arrived. More than 2 000 Japanese and 300 Americans died in the battle.The expedition is an effort started by the late Paul Allen, the billionaire co-founder of Microsoft. For years, the crew of the 76m Petrel has worked with the US Navy and other officials around the world to locate and document sunken ships. It has found more than 30 vessels so far.