Cook Island is the central and largest island of the Southern Thule island group, part of the South Sandwich Islands in the far south Atlantic Ocean. Southern Thule was discovered by a British expedition under Captain James Cook in 1775. Cook Island was named for Cook by a Russian expedition under Fabian Gottlieb von Bellingshausen, which explored the South Sandwich islands in 1819–1820.
The island was surveyed in 1930 by Discovery Investigations (DI) personnel on Discovery II, who charted and named many of its features.
Swell Point is a small, narrow point on the island's east coast, near its southeast extremity, south of Resolution Point. It was named descriptively.