Intergalactic space

"That's...our galaxy. We're beyond the rim."

- John-117 on Installation 00

Intergalactic space is the region of space between galaxies. The volume of intergalactic space is mostly empty and has an extremely low density. In rare cases, naturally occurring objects such as stars may be found outside galaxies.

Installation 00 was located in the intergalactic void. The Forerunners rarely ventured into intergalactic space, as they were satisfied with the resources of the Milky Way Galaxy. The objects closest to the Milky Way Galaxy are the Magellanic Clouds, two small satellite galaxies where the Flood were said to have first arrived to the Galaxy.