Antarctica is surrounded by ocean waters that play a tremendous role in its climate. The world’s most powerful current circulates around the Antarctic, preventing warm subtropical surface waters from reaching the coast of the continent, thus perpetuating its glacial state. At the same time, the circulation of global oceans brings deep waters to the edge of Antarctica. These deep waters have been warming strongly over the last 50 years, disrupting the balance between the ocean and the continent. Recent Antarctic expeditions have provided data allowing scientists to estimate the important implications of this disruption.