Deception Island is a 14 km wide, ring-shaped volcanic island at the south-western end of the South Shetland Islands, NE of Graham Land Peninsul. It is one of the most well-known active volcanoes of the Antarctic region. Deception Island is a sea-filled caldera with a diameter of 7 km with a narrow entry (Neptunes Bellows) on the SE side. The island forms a natural harbour and was a popular base for whaling ships in the 19th century. There were huts and shelters and, later, scientific observatory stations, which were damaged during the last eruptions in 1967 and 1969.

Deception Island volcano is located on the axis of the Bransfield Rift spreading center. Numerous volcanic vents are located along ring fractures circling the low island and were the sites of historic eruptions.

The volcano contains maars on the shores of 190-m-deep caldera (Port Foster), the largest of which is 1-km-wide Whalers Bay at the entrance to the harbor.