Cockburn Island is an oval island 2.7 kilometres (1.7 mi) long, consisting of a high plateau with steep slopes surmounted on the northwest side by a pyramidal peak 450 m (1,476 ft) high, lying in the north-east entrance to Admiralty Sound, south of the north-east end of the Antarctic Peninsula.

It was discovered by a British expedition (1839–43) led by Captain James Clark Ross, who named it for Admiral Sir George Cockburn, then serving as First Naval Lord (commander-in-chief of the Royal Navy).

The first stage was a subglacial hyaloclastic eruption under a thick ice cap, which shattered the lava into glass, ash and sand, which has since weathered to yellow palagonite layers.

The final phase was subaerial basalt lava flows on top of the previous volcanic deposits after the lake drained or boiled away.

[5] Joseph Dalton Hooker, at the time a junior naturalist stationed aboard HMS Erebus, made a series of botanical collections on the island in 1843.