Buckle Island is one of the three main islands in the uninhabited Balleny Islands group located in the Southern Ocean. It lies 25 km (16 mi) north-west of Sturge Island and 8 km (5 mi) south-east of Young Island, some 110 km (68 mi) north-north-east of Belousov Point on the Antarctic mainland. The island forms some parts of the Ross Dependency, claimed by New Zealand.

The island is roughly triangular in shape, with long east and west coasts and a short north coast. It is about 3 nmi (6 km; 3 mi) wide in the north, with a maximum length of 13 nmi (24 km; 15 mi). It is of volcanic origin, and is still volcanically active, the last eruption being in 1899.

The northernmost point is Cape Cornish. Several small islets also lie in the channel separating Cape Cornish and Young Island, the largest of which is Borradaile Island. Several small islets lie off the island's southern extremity, Cape McNab, including Sabrina Islet and the 80-metre (262 ft) tall stack of The Monolith. Both Buckle Island and Sabrina Islet are home to colonies of Adelie and chinstrap penguins.

• List of Antarctic and subantarctic islands

• W.E. LeMasurier; J.W. Thomson (1990). Volcanoes of the Antarctic Plate and Southern Oceans. American Geophysical Union. p. 512 pp. ISBN 0-87590-172-7.

• "Buckle Island". Global Volcanism Program. Smithsonian Institution. Retrieved 24 June 2021.