Tributes are flowing for the five men killed on board the Titan sub in what US officials say was a “catastrophic implosion.”

The victims were Hamish Harding, 58, Shahzada Dawood, 48, and his son Suleman Dawood, 19, Paul-Henri Nargeolet, 77, and Stockton Rush, 61, the BBC reports.

Their families have expressed “profound grief” and paid tribute to their exploration endeavours.

A robotic diving vehicle found major fragments of the sub on the seafloor about 1,600ft (480m) from the Titanic shipwreck on Thursday.

It’s emerged the US Navy originally detected “an acoustic anomaly consistent with an implosion” shortly after the Titan lost contact on Sunday.

James Cameron, director of the 1997 Titanic film who has completed 33 dives to the wreck, said he suspected a disaster after the sub went missing.

The sombre find ends a multinational five-day search which spanned more than 20,000 sq km of ocean.