Weddell Sea, an arm of the Atlantic Ocean off the coast of Antarctica. It lies south of the Antarctic Circle, largely between the Antarctic Peninsula and Coats Land. Most of the sea, especially in the south, is covered by huge sheets of ice, the largest of which are the Ronne, Filchner, and Larsen ice shelves. Many scientific research stations are located along the Antarctic Peninsula. The Weddell Sea was discovered by the British navigator James Weddell in 1823.