Auckland Island is the main island of the Auckland Islands, an uninhabited archipelago in the south Pacific Ocean belonging to New Zealand.

The island has an approximate land area of 510 km², and is 42 kilometres long. It is notable for its steep cliffs and rugged terrain, which rises to over 600 metres. Prominent peaks include Cavern Peak (650 M), Mount Raynal (635 m), Mount D'Urville (630 m), Mount Easton (610 m), and the Tower of Babel (550 m).

The southern end of the island broadens to a width of 26 kilometres. Here, a narrow channel known as Carnley Harbour (on some maps the Adams Straits) separates the main island from the smaller Adams Island. The channel is the remains of the crater of an extinct volcano, and Adams Island and the southern part of the main island form the crater rim.