Blackwater City is a map in the multiplayer mode in Up Your Arsenal. It is very similar to the area of Blackwater City seen in the Galactic Rangers' Operation: BLACK TIDE. It is a mirrored map in which each base exists on an island either at the top or bottom end of the map respectively. From the starting base's island, a ramp at the end leads up to a large, round platform, where a Holoshield Glove, a Mine Glove, Charge Boots, and a player-controlled turret can be found. A wide bridge at the end of this platform leads to an opposing round platform, with versa-targets adjacent to the bridge also used for traversal.
To the back of the central platforms are bending bridges that lead up to small, elevated platforms containing well-guarded nodes. The node on the right from the closest base contains a Minirocket Tube and a Lava Gun, while the node on the left from the closest base contains a Flux Rifle and a Morph-o-Ray. Versa-targets exist across these platforms to reach the platform on the opposite side that is closest to the nearest base.