Who's onboard the Titan submersible ? ?
An adventurer and a British businessman travelling with his son were among those on the Titanic sub.
www.bbc.com
British adventurer Hamish Harding 58, chairman of aircraft firm Action Aviation, is a renowned explorer who has flown to space and holds three Guinness World Records.
In a statement released on Tuesday, the Dawood family in Pakistan said: "Our son Shahzada Dawood and his son, Suleman, had embarked on a journey to visit the remnants of the Titanic in the Atlantic Ocean.
"As of now, contact has been lost with their submersible craft and there is limited information available."
French explorer Paul-Henry Nargeolet is also thought to be on board, according to a Facebook post by Mr Harding before the dive started
Stockton Rush, chief executive of OceanGate, is also widely reported to be on the vessel.