Titanic sub implosion: Was the deep ocean vehicle safe?

Because it operated in deep-sea international waters, the Titan was not subjected to much regulation [OceanGate Expeditions/Reuters Handout]

The implosion of a submersible touring the deep-sea wreckage of the Titanic, killing all five passengers on board, has prompted questions about the regulations overseeing such voyages — and whether the vehicle itself was safe.

On Friday, the company responsible for the tour, OceanGate Expeditions, defended the decisions of its chief executive Stockton Rush, who died on board the submersible.