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 5490 metres of water in the Pacific Ocean more than 2090km northwest of Pearl Harbor.

The 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 on 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.

"We read about the battles, we know what happened. But when you see these wrecks on the bottom of the ocean and everything, you kind of get a feel for what the real price is for war," said Frank Thompson, a historian with the Naval History and Heritage Command in Washington, DC.

"You see the damage these things took, and it's humbling to watch some of the video of these vessels because they're war graves," he said.

Until now, only one of the seven ships that went down in the June 1942 air and sea battle - five Japanese vessels and two American - had been located.

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 World War II.

The battle was fought between American and Japanese aircraft carriers and warplanes about 320km off Midway Atoll, a former military installation that 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 2000 Japanese and 300 Americans died.

The expedition is an effort started by the late Paul Allen, the billionaire co-founder of Microsoft. For years, the crew of the 76-metrre 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.

Kraft says the crew's mission started with Allen's desire to honour his father's military service. Allen died last year.

Australian Associated Press