An expert has given three possible explanations as to what happened to the submarine-like vessel that vanished in the middle of the Atlantic Ocean.
Four people and the vessel's pilot paid around $250,000 (around £195,000) in the hope of seeing the Titanic shipwreck which lies 12,500ft beneath the Atlantic's surface, off the coast of Canada.
But the OceanGate Expeditions vessel lost contact around an hour and 45 minutes after it submerged on Sunday and rescuers warn they may not reach the ocean craft before its oxygen supply runs out.
