Montagu Island is the largest of the South Sandwich Islands, located in the Weddell Sea off the coast of Antarctica at latitude 58° 25' south, longitude 26° 23' west.

NASA satellite photograph of Montagu Island

The desolate, uninhabited island measures approximately 12 kilometres by 10, with over 90% of its surface permenantly covered in ice. The volcano Mount Belinda is its most notable geographic feature, rising to 1370 metres above sea level. Mount Belinda was believed to be inactive prior to the sighting of low-level ash emission and suspected lava effusion in 2002 by the British Antarctic Survey.

The island was first sighted by James Cook in 1775, and named after John Montagu, the 4th Earl of Sandwich and the First Lord of the British Admiralty at the time of its discovery.