"Like tree rings, growth rings in corals indicate age. They also reflect changes over centuries and millennia in ocean chemistry and the ocean environment," Ron Thresher from the Australian government's Commonwealth Scientific & Industrial Research Organisation (CSIRO) said on Thursday.

"Deep ocean corals are a litmus test of the deep ocean when it comes to identifying how temperature and salinity have changed over decades and centuries," Thresher, who will set sail on Friday, said in a statement announcing the project.

"We hope to track two influential elements on the global climate system -- the formation of water masses at the Antarctic coast and the circulation of the Southern Ocean," he said.

The submersible Autonomous Benthic Explorer, on loan from the Woods Hole Oceanographic Institution in the United States, will be launched from an Australian marine research ship during the 23-day voyage. The submersible can reach depths of 4 kms (2.5 miles) and can stay underwater for seven hours.

CSIRO marine scientist Alan Williams said a dive to 2.5 kms will allow scientists to view biodiversity at depths never seen before in Australian waters.