The five people on board the Titan sub are believed to have died, the operating company behind the submersible has announced.
In a statement, OceanGate said: "We now believe that our CEO Stockton Rush, Shahzada Dawood and his son Suleman Dawood, Hamish Harding, and Paul-Henri Nargeolet, have sadly been lost.
"These men were true explorers who shared a distinct spirit of adventure, and a deep passion for exploring and protecting the world’s oceans. Our hearts are with these five souls and every member of their families during this tragic time. We grieve the loss of life and joy they brought to everyone they knew."