Antarctica is not owned by any country, per the Antarctic Treaty. Before the Antarctic Treaty was signed, seven countries claimed parts of the continent, including Australia, the United Kingdom, Chile, Argentina, Norway, France and New Zealand. The treaty recognizes none of these claims.
Antarctica is surrounded by the Southern Ocean. The International Hydrographic Organization created the Southern Ocean from parts of the Indian, Pacific and Atlantic Oceans in 2000. The Southern Ocean is the fourth largest ocean in the world, surpassing the Arctic Ocean.