Deception Island

Sail through a 500 metre gap into a live volcano

Deception Island, in the South Shetlands off the Antarctic Peninsula, is the exposed top of an active shield volcano 30 km across. The island itself is a horseshoe about 15 km wide whose centre the sea has flooded, forming Port Foster, a bay 10 km long and 7 km wide. Ships come in through Neptune's Bellows, a gap just 500 metres wide, with Ravn Rock lying 2.5 metres under the water in the middle of the channel. The American sealer Nathaniel Palmer explored the bay on 15 November 1820 and named the island for its trick: from outside it looks ordinary, and only the narrow entrance shows it to be a ring around a flooded caldera.

The caldera collapsed sometime between 8,300 and about 3,980 BC, and a 2019 study of its magma system ranks it with Krakatoa and Santorini in size. More than 20 explosive eruptions have been recorded in the last two centuries. Ash from older, far larger blasts has turned up in South Pole ice cores, and British Antarctic Survey researchers found that across 7,000 years, three of five growth phases in the penguin colonies on Ardley Island, 120 km away, ended in crashes caused by its eruptions.

Sealers used the harbour as a base in the early 1820s, until the fur seals were hunted nearly out. Whalers followed. In 1906 the Norwegian-Chile company Sociedad Ballenera de Magallanes began working from Whalers Bay, several hundred men lived here through the summers, and in 1912 the Norwegian firm Hektor built a station ashore, the only successful shore-based industry ever to operate in Antarctica. Its cemetery, the largest on the continent, held graves for 35 men. Factory ships that could haul whole whales aboard undercut it, and the Hektor factory closed in early 1931. On 16 November 1928 Hubert Wilkins took off from a beach airstrip here on the first successful flights in Antarctica.

In December 1967 an eruption forced the Chilean, Argentine and British bases to evacuate, and eruptions in 1969 and 1970 followed. The 1969 mudflows tore the middle out of Biscoe House at Whalers Bay, where rusting boilers and tanks still stand. Unrest returned in 1992, 1999 and 2014-2015. Argentina and Spain now run summer stations, more than 15,000 visitors come each year, and the island is administered under the Antarctic Treaty System.