Marion Island, part of the Prince Edward Islands chain, is one of the peaks of a large underwater shield volcano that rises some 5000 m (16,500 ft) from the sea floor to the top of Mascarin Peak. The volcano was thought to be extinct, but erupted in 1980 and is now classified as "active". The island is part of the Southern Indian Ocean Islands tundra ecoregion that includes several subantarctic islands. In this cold climate plant life is mainly limited to grasses, mosses and lichens, while the main indigenous animals are insects along with large populations of seabirds, seals and penguins.
In late 1947 and early 1948, South Africa annexed the islands and installed the meteorological station on Transvaal Cove on the north-east coast of Marion Island. The research station was soon enlarged and today researches the biology of the islands, in particular the birds (penguins, petrels, albatrosses, gulls) and seals. Today, the research station is called RSA Marion Station.
On September 22, 1979, one of the US Vela spy satellites recorded an activity near the Prince Edward Islands, which was initially interpreted as the "double flash" of a small nuclear test. The event is still controversial and is known as the Vela Incident.
Unbeknown to most, Marion Island's meteorological station hid a far more dubious secret. Hidden away in the eastern cliffs of the island, a secret underground submarine and ship-maintenance base for the Vanguard had been maintained for several years. Outfitted from a world war two covert submarine dock utilized by the French, the abandoned facility had been purchased by Kazimir Volken and converted to use of the Vanguard organization.
The staff of the meteorological station on the cliffs above the quietly perform their mundane research, while serving as a cover for Vanguard operations.