The second search for missing Malaysia Airlines flight MH370 ended Tuesday after a fruitless 90-day sweep of the southern Indian Ocean.
The US-based company that conducted the hunt, Ocean Infinity, said it had covered 112,000 square kilometers of the ocean floor, but ultimately found nothing.
The aircraft disappeared in 2014 carrying 239 people from Kuala Lumpur to Beijing in one of the world's biggest aviation mysteries.
Ocean Infinity took over after the initial search failed on a no-find, no-fee basis.
"Part of our motivation for renewing the search was to try to provide some answers to those affected. It is therefore with a heavy heart that we end our current search without having achieved that aim," Ocean Infinity CEO Oliver Plunkett said in a statement.
"There simply has not been a subsea search on this scale carried out as efficiently or as effectively ever before."
An initial search, carried out by Malaysia, China and Australia, was called off in January last year. It was estimated to have cost some 200 million Australian dollars ($151 million).
"Whilst clearly the outcome so far is extremely disappointing, as a company, we are truly proud of what we have achieved both in terms of the quality of data we've produced and the speed with which we covered such a vast area," Plunkett said.
Several theories on what might have happened to the ill-fated flight have been put forward, including pilot suicide.
Australian investigators who led the joint search for the jetliner dismissed that theory and have defended their belief that the plane's disappearance was due to an accident.
The only physical sign of the plane has been debris that washed up in eastern Africa and nearby islands, far from where experts believed the flight disappeared. A wing fragment and part of the plane's flaperon are among the remnants that have turned up.
Despite the lack of results, Ocean Infinity hasn't ruled out the possibility of eventually renewing the search.
"We sincerely hope that we will be able to again offer our services in the search for MH370 in future," Plunkett said in the statement.
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