Big Shell is the offshore facility where most of Metal Gear Solid 2: Sons of Liberty takes place.
The Big Shell is presented as an oil-spill cleanup and decontamination complex in New York Harbor. During the game, terrorists seize the facility and hold hostages, drawing Raiden into an operation that gradually reveals a much larger conspiracy involving the Patriots.
Its interconnected platforms provide the game’s main environment. Players move through areas such as Shell 1 and Shell 2, crossing bridges and navigating restricted industrial spaces. The facility’s public environmental purpose contrasts with its hidden military and information-control functions.
Big Shell is distinct from Shadow Moses, the Alaskan island setting of the first Metal Gear Solid. It is also different from the offshore base known as Mother Base, which is associated with later entries and the Diamond Dogs organization.