Japanese university researchers have begun searching for 4 civilian ships that were sunk by US attacks in the East China Sea during World War Two.
A team from Kyushu Institute of Technology arrived on Friday night at the site of where one of the wrecks is thought to be located.
The "Taiyo-maru" was a large German-made passenger ship that was attacked by a US submarine while heading toward occupied territory in Southeast Asia in 1942. 817 people died.
The researchers lowered sonar equipment to a depth of more than 100 meters to survey the sea bottom. If they can confirm the ship's existence, they plan to send down an underwater drone to take pictures.
The researchers also plan to look for the "Rima-maru", which was attacked in 1944, killing more than 2,700 people. The other two ships are the "Seiron-maru" and "Fusei-maru".
About 2,500 civilian ships were believed to have been sunk during the war. Some records show that about 120,000 crew members and civilians were killed.
But in many cases, not much has been disclosed because of military secrecy.
The search will continue for about 5 days.