As US and Canadian authorities continue search efforts overnight, it is still not clear what happened to the missing submersible, why it lost contact with crews on the surface, and where or how deep it might be.
A Pakistani father and son are on board a submersible carrying five people to see the wreck of the Titanic at the bottom of the North Atlantic Ocean, according to a statement released by the family Tuesday.
The missing submersible's trip to the wreckage of the Titanic was the final expedition of five such tours scheduled for this year, an archived version of the operator's website said.