Cook Island is the central and largest island of Southern Thule

Southern Thule

Southern Thule is a collection of the three southernmost islands in the South Sandwich Islands: Bellingshausen, Cook, and Thule . Southern Thule is British territory, though claimed by Argentina. The island group is barren, windswept, bitterly cold, and uninhabited. It has an extenzive EEZ rich...

, part of the South Sandwich Islands

South Georgia and the South Sandwich Islands

South Georgia and the South Sandwich Islands is a British overseas territory and overseas territory of the European Union in the southern Atlantic Ocean. It is a remote and inhospitable collection of islands, consisting of South Georgia and a chain of smaller islands, known as the South Sandwich...

 in the far south Atlantic Ocean

Atlantic Ocean

The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...

. Southern Thule was discovered by a British expedition under Captain James Cook

James Cook

Captain James Cook, FRS, RN was a British explorer, navigator and cartographer who ultimately rose to the rank of captain in the Royal Navy...

 in 1775. The island was named for Cook by a Russian expedition under Bellingshausen

Fabian Gottlieb von Bellingshausen

Fabian Gottlieb Thaddeus von Bellingshausen was an officer in the Imperial Russian Navy, cartographer and explorer, who ultimately rose to the rank of Admiral...

, which explored the South Sandwich Islands in 1819–20.

Cook Island measures about 6 by wide. It is heavily glaciated and uninhabited. Its highest peak, Mount Harmer, rises to 1115 m (3,658.1 ft).