[1] Former names for the port have remained for other features in the same archipelago — Williams Point and Yankee Harbor.
The centre of Deception Island is a caldera, formed by a gigantic volcanic eruption and later flooded.
This has created the 10 by 7 km (6.2 by 4.3 mi) basin-like harbour of Port Foster.
The entrance to Port Foster is only 560 m (1,840 ft) wide and is named Neptune's Bellows.
The benthic zone of Port Foster is of great ecological interest due to the natural disturbance induced by the volcanic activity.