THERE was no treasure chest, no Black Pearl, no Jack Sparrow and no MH370 - yet.

What there was were two geological formations that had been identified as points of interest.

The Ocean Infinity-leased Seabed Constructor, the high-tech vessel searching for MH370, had returned to revisit those points of interest discovered on its first sweep and turned off its satellite tracking system so as not to give the relatives false hopes.

The idea was to try and prevent wild speculation it had found the plane.

What happened was exactly the opposite, with bizarre stories, laced for good measure with a treasure chest.

A source in London, said the 'treasure chest' was a throw-away joke from Fugro's Paul Kennedy, the former search head.

"'PK' made some flippant, closing remarks during his presentation at the WA SSSI 2015 conference several years ago and this was picked up and became speculation that spread across the internet like wild fire," the source said.

The Seabed Constructor left the search area on February 4 and arrived at Henderson today. It will depart on February 12 to resume the search.

The MH370 Response Team said 7500 sq. km of the 25,000 sq. km identified in the Australian Transport Safety Bureau’s final report on the original search had been swept by the ship.

Camera Icon Recovered debris has led experts to identify new search sites for MH370. Credit: AFP

The Seabed Constructor began the search January 21 and uses eight Hugin autonomous underwater vehicles to scour the seabed.

Ocean Infinity has a "no find, no fee" deal with the Malaysian government.

It will be paid $US20 million if plane is found in the 5000 sq. km primary search area, $US30m in the 10,000 sq. km secondary zone and $US50m in the 10,000 sq.km tertiary area.

The three zones make up the 25,000 sq.m area defined by the ATSB and other experts.

Ocean Inifinity will get $US70m if it locates the wreckage in outside that 25,000 sq.km zone where a number of experts have suggested it is.

The University of Western Australia’s Professor Charitha Pattiaratchi said last year that its reverse drift modelling put the location of MH370 "at Longitude 96.5° E Latitude 32.5° S with a 40km radius."

Some members of the global "Independent Group" of experts, believe it may be even further north and a map on the Malaysian update identifies two "site extensions", one of which ranges north of 29° S.

The Ocean Infinity search will cover all areas.