Undervault

Undervault is a small settlement in a cave just north of Arsia Mons.

Summary
Undervault was one of the first independent colonies on Mars and there was enough room for 64 people. There wasn't much science going on in Undervault other than the fact that they were trying to pressurize the whole cave. They succeeded with this and built a huge underground farm powered by UV lights.

Sometime between 2166 and 2167, a 600km tunnel was built between Undervault and The Tube.

Only 15 people were RH- blooded and survived the virus. They stayed in Undervault and started collaborating with The Tube. All equipment was moved into the cave once things were going bad so it is difficult to find Undervault. This has resulted in fewer raids and a very peaceful settlement.