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.