BOSTON - The family of British businessman Hamish Harding, one of five passengers who died on board a submersible visiting the wreck of the Titanic, paid tribute on Thursday to a "passionate explorer".

All five people on the vessel died after it suffered what the US Coast Guard said was a "catastrophic implosion" in the ocean depths, ending a multinational search-and-rescue operation that began when the tiny craft went missing in the North Atlantic four days ago.

Passenger Harding, 58, was a British aviation tycoon with three Guinness World Records.

A statement from his family and his company Action Aviation said they were "united in grief with the other families who have also lost their loved ones on the Titan submersible".

"He was one of a kind and we adored him," the statement said.

"He was a passionate explorer -- whatever the terrain -- who lived his life for his family, his business and for the next adventure," the statement said, describing Harding as a "loving husband and a dedicated father to his two sons".

"What he achieved in his lifetime was truly remarkable and if we can take any small consolation from this tragedy, it's that we lost him doing what he loved," the statement added.

This undated image courtesy of OceanGate Expeditions, shows their Titan submersible launching from a platform

Harding founded Action Aviation -- a company that buys and sells aircraft with offices in Dubai and London's Stansted airport -- with UK media reporting that the UAE-based businessman was a billionaire.

He was previously based in the Indian city of Bengaluru for five years as managing director of a logistics company before establishing Action Aviation in 2004.

His Guinness records are for longest duration and distance traversed at full ocean depth by a crewed vessel, and the fastest circumnavigation via both poles by plane.

A year ago, he became a space tourist through Amazon founder Jeff Bezos's Blue Origin company.

Harding was joined on board by French submarine expert Paul-Henri Nargeolet, Pakistani-British tycoon Shahzada Dawood and his son Suleman, and Stockton Rush, CEO of the sub's operator OceanGate Expeditions.

Rear Admiral John Mauger told reporters in Boston on Thursday that analysis showed debris found on the seafloor 500 metres (1,600 feet) from the bow of the Titanic was consistent with the implosion of the sub's pressure chamber.