Southern Ocean (SO)

The Southern Ocean (SO) realm is the vast, cold marine region surrounding the continent of Antarctica. It is defined by the Antarctic Circumpolar Current, the world's strongest ocean current, which effectively isolates its waters from warmer northern oceans. This realm is home to highly specialized life forms adapted to near-freezing temperatures, with Antarctic krill serving as the cornerstone of its food web. It supports massive populations of whales, seals, and penguins that rely on its nutrient-rich upwellings. The realm includes a range of habitats from deep-sea basins to shallow shelf areas covered by seasonal sea ice. As a major driver of global ocean circulation and a massive carbon sink, the Southern Ocean plays a critical role in Earth’s climate system.