The depths of the Indian Ocean off the coast of Australia have been scoured for four years by searchers looking for the remains of missing Malaysia Airlines Flight 370.
While the missing airliner is yet to be found, the unprecedented sonar hunt has instead yielded two ancient shipwrecks and historians say they may have solved the 19th century mystery of what happened to the vessels, which were carrying loads of coal.
Maritime historians published details Thursday of the locations where the ships were found in a 274,000-square-mile search area for the Boeing 777, which was carrying 238 people, was lost in 2014.
The wrecks were 22 miles apart and 1,440 miles southwest of Australia. The area was littered with coal and more than 2.3 miles below the surface.
Underwater drones took images of the debris and retrieved a coal sample. The Western Australian Museum report said the coal was probably from Britain.
One of ships may have sunk because of an explosion, a common catastrophic event in those times in the transport of coal, said maritime archaeology curator Ross Anderson.
The other remains were more intact, lying upright.
"Historical research into all 19th century merchant ships that disappeared in international waters is incomplete so we cannot conclusively determine [the] identity of the individual ships," Anderson said.
"However, we can narrow the possibilities to some prime candidates based on available information from predominantly British shipping sources."