Bunker Charlie is set on an island near the south of the World Map.
There is a CAC Card C for access to the Bunker, obtainable as random loot.
An interesting quirk is that Bunker Charlie is marked with a green marker, unlike Bunker Alfa and Bunker Bravo, which are marked with yellow markers. Some believe the Bunker is still in control of the military and currently active.
As of the current version, players cannot access Bunker Charlie, as the Mi-24 Helicopter is uncraftable.