Researchers from five countries are setting sail from Hobart on a mission to track down blue whales in the Southern Ocean.

Little is known about the largest creatures to have lived on earth and the 18 researchers will be using new technology to find them.

The 30 metre long mammals, weighing 180 tonnes, have tongues weighing as much as an elephant and their hearts are bigger than a car.

Mike Double from the Marine Mammals Centre says despite their size, blue whales have eluded researchers for decades.

"To give you some context, in 30 years of studying these whales there were 220 sightings," he said.

"They were very close to extinction in the 1970s, and we think they're recovering, but we know little about their recovery at the moment and that's why we're starting this international project, to deliver a new abundance estimate for this species."

It is now thought there are thousands in the Southern Ocean, but scientists know little about their breeding patterns, or how long they live.

The team will be using acoustic techniques developed by scientists in the United States military and its ultimate goal is to tag a blue whale and track its movements on satellite.

Marine mammal acoustician, Brian Miller, says the technology should make the search easier.

"Underwater listening devices transmit the sounds that they hear back to the ship over a radio link and then we sit on the boat with our headphones on listening for whale sounds to come in."

Mike Double says that does not mean the team is guaranteed of success.

"There is always a risk that we won't find them, but even in that we will be learning something about how we're approaching this problem."