Antarctica is encircled by the planet's strongest current which helps keep the frozen continent cool and hotter northern waters at bay.
But naturally occurring "leaks" in the Antarctic Circumpolar Current, dubbed the continent's dam, have in recent times allowed more water in.
Scientists aboard CSIRO research vessel Investigator are embarking on a month-long trip to the Southern Ocean in the hope of understanding why.
Antarctica this year likely set a new record for the lowest annual amount of sea ice around the continent, breaking the previous mark by a million square kilometres.
"There has been a lot of discussion about the sea ice and the massive reduction," University of Tasmania associate professor and voyage co-chief scientist Helen Phillips told reporters.
"What is surprising to scientists is the speed at which these changes are happening.
"This incredible reduction in the sea ice was way outside the bounds of what we might have expected."
The Antarctic Circumpolar Current (ACC) generates whirling eddies, circular movements of water, which are considered prime suspects for warmer waters seeping towards the pole.
"(The current) is like a big dam holding back the heat to the north and allowing Antarctica to stay cold, but it is leaky in a few places," Dr Phillips said.
"It has always been leaky but we're seeing more heat coming through in recent times".
Five "eddy gates" have been identified around the Antarctic Circle.
"We're going to track down those small features that we think explain the heat seeping into polar waters," voyage chief scientist Dr Benoit Legresy said.
Dr Legresy said the flow of the ACC was 100 times stronger than all the world's rivers combined.
Scientists will for the first time validate imagery of the Southern Ocean taken by a satellite developed by NASA and French space agency Centre National d'Etudes Spatiales (CNES).
Dr Rosemary Morrow, CNES satellite ocean lead, said the imagery was a breakthrough.
"Our first images already show the incredible two-dimensional structure of ocean eddies and fronts, and how they are stretched and strained by the turbulent ocean," she said.
"These small-scale ocean dynamics are key in stirring heat and carbon across the ocean, but also in pumping them deep into the ocean interior."
The Investigator will leave Hobart this week and is scheduled to return on December 20.
