The Weddell Sea is part of the Southern Ocean and contains the Weddell Gyre. Its land boundaries are defined by the bay formed from the coasts of Coats Land and the Antarctic Peninsula. The easternmost point is Cape Norvegia at Princess Martha Coast, Queen Maud Land. To the east of Cape Norvegia is the King Haakon VII Sea. Much of the southern part of the sea, up to Elephant Island, is permanent ice, the Filchner-Ronne Ice Shelf. The sea is contained within the two overlapping Antarctic territorial claims of Argentina, (Argentine Antarctica) and Britain (British Antarctic Territory), and also resides partially within the territorial claim of Chile (Antarctic Chilean Territory). At its widest the sea is around 2,000 km across, in area it is around 2.8 million km².

In his 1950 book The White Continent, historian Thomas R. Henry writes, "The Weddell Sea is, according to the testimony of all who have sailed through its berg-filled waters, the most treacherous and dismal region on earth. The Ross Sea is the relatively peaceful, predictable, and safe." He continues on for an entire chapter, relating myths of the green-haired merman sighted in the sea's icy waters, the inability of crews to navigate a path to the coast until 1949, and treacherous "flash freezes" that left ships, such as Ernest Shackleton's Endurance, at the mercy of the ice floes.