Australian-led efforts to find the Malaysia Airlines Boeing 777, which vanished on March 8 with 239 people on board, are concentrated on a stretch of water 2,500 kilometers (1,500 miles) southwest of Perth.

It is little traversed by maritime traffic, and when alerts went out to merchant shipping in the area on Tuesday, the nearest vessel was two day's journey away.

It is also windy, lashed by huge waves.

"Very harsh conditions, once you get there the influence of Antarctica... starts to come clearly on the ocean," said Erik van Sebille, an oceanographer at Sydney's University of New South Wales.

Van Sebille, who was on a research ship in the area in December, said even in calm conditions the place was challenging and with the southern hemisphere's autumn approaching, it was set to deteriorate.

"It's not an area where you would like to be for a very long time, to spend weeks searching for a plane," he told AFP.

"The place couldn't have been worse, but also the timing couldn't have been worse. Had it been a few months earlier, the seas are much calmer, much easier to work in."

Nathan Bindoff, professor of physical oceanography at the University of Tasmania, said: "The Indian Ocean sector is a region that has strong winds and big waves.

"It is the windiest sector of the southern ocean."

Bindoff said vessels typically saw only one other ship on a 50-day voyage in the area, and then most likely closer to Antarctica and its research bases than the area where the potential wreckage was spotted.

"In some ways there are more eyes near Antarctica than there are in this part of the southern ocean," he said.

BA/BA