To tell the truth, I've never been to Idaho myself, but I'm guessing the natural terrain is mainly mountainous and evergreen trees. The prison itself is not like most other supermax prisons. It has concrete outer walls, lined with sniper towers and machine gun nests, and inside are a series of electrified fencing patrolled by heavily armed jeeps. For areas not made for prison inmates when they're out for a time, there are hangars for helicopters and some surprises kept, a storage garage where the ground vehicles are parked, a barracks for prison guards, and a cluster of dug-in anti-aircraft artillery. The command for the prison itself is from an arrangement of buildings, and Ms (not DR) Julia Race is the head warden of the prison and head of security for the base underneath. Besides the one and only gate and the helicopters for entrance, the only other entrance to the underground base is a guarded subway system connecting to a business complex also guarded by Dragonstorm.
The placement of the base itself is in the middle of a field nearly a mile from the tree line, and a river down a gorge to the northwest of the prison.