Diego Garcia is an atoll located in the central Indian Ocean It also hides the Fifth Vertex.
During the periods that Diego Garcia was under French and British control, both nations made their own attempts to reach the bottom of its Vertex, however they would always set off the trap system protecting it.
When the U.S. Government bought the atoll from the British, they made it a naval base. The atoll's Vertex was under their control for years, during which they made several attempts to reach the inverted pyramid's peak, however they fared no better than the French or British. However, the Americans' expert on the Machine, Felix Bonaventura, was able to use a pair of cranes to examine the inverted pyramid up close, and was able to learn much regarding the other Vertices because of the symbols carved into its flanks.
In the interim between the laying of the Second and Third Pillars, Wolf and his CIEF forces based out of Garcia's naval headquarters. The U.S. Marine Astro, whom had worked with Jack's team until he was captured and drugged, was kept there until he awoke and convinced that he was being decieved so that he would join Wolf's team.
After the final Pillar was placed at the Sixth Vertex, the Fifth Vertex beneath Diego Garcia activated once again. This time, as the beam of light it emitted struck the Earth's iron core, it was accompanied by the light beam ignited from the other five Vertices, causing a series of harmonic waves that repelled the Dark Sun.
The Fifth VertexEdit
The Fifth Corner of the Machine, the Realm of the Sea Lords, is located beneath Diego Garcia. Like every other Vertex, there is the inverted pyramid of the Machine, which is set above a seemingly bottomless chasm. There is a set of paths through which the Pillar setter must have the Pillar itself to reach the bottom safely. If the master trap is set off, a wave of water enters circular shape cavern and runs around it, picking up the intruder and washing them into the abyss below the inverted pyramid.