An advanced subsea vessel in Swire Seabed's fleet has brought conspiracy theorists out of the social-media woodwork.

The 115-metre Seabed Constructor (built 2014) went dark on tracking systems, witnessed by a number of amateur ship-watchers.

The ship is being used by Texas-based geophysical company Ocean Infinity to search for the wreckage of the missing Malaysia Airlines Flight 370 (MH370) with six ultra-deepwater drones.

On 10 January, Ocean Infinity entered into a “no cure, no pay” agreement with the Malaysian government. The US outfit stands to earn up to $70m if it can find the MH370 within 90 days.

Ocean Infinity began its search on 22 January, with aviation and shipping enthusiasts plotting its moves with automatic information system (AIS) data and posting on Twitter about its progress. But on 1 February, the Seabed Constructor stopped sending AIS signals for about 80 hours.

And so began the internet rumour mill, which was then amplified by numerous global media outlets, and the conspiracy theories ranged into the bizarre.

At the end of a previous three-year search by Fugro, one of the Dutch company’s officials said they had captured images of a sunken treasure chest. This is thought to have been made in jest, but some observers took it as gospel.

Twitter pundits suggested that Ocean Infinity diverted the ship, switching off its AIS to grab the treasure unseen, which makes little sense if it has only limited time to find the main prize.

Others believe the ship may have actually vanished. “The ship searching for MH370 has disappeared, just like the airliner,” blogger The Outer Light said last week. “This is like something out of the X-Files.”

Most of the news stories and comments referred to the Twitter-feed of US-based Kevin Rupp, who had been tracking the AIS updates as a hobbyist and flagged up the blackout.

Last week, he had finally had enough.

“I’m getting more than a little tired of seeing my tweets being used in articles about alleged treasure hunts and conspiracy theories. I don’t want anything to do with that. I’m just trying to keep track of what’s happening,” Rupp posted.

The drama even prompted Malaysia's transport minister, Sri Liow Tiong Lai, to hold a press conference last week to reassure citizens that the search for the MH370 wreckage was "going smoothly".

“There has been concern that the Seabed Constructor could not be located. That’s just not true,” he said, pointing out that the ship was refuelling near Perth.