Coilfang Reservoir is an instance located in Zangarmarsh. The structure itself is a subterranean water pumping station, operated by the Naga. The dungeon is made up of gigantic caverns with huge pipes descending from the ceiling powered by titanic crystal capacitors. While the entrance to the Reservoir is underwater, the instance itself is only partially submerged, similar to the Blackfathom Deeps.

It is also the only Coilfang Reservoir instance that a player can run in Normal mode and receive Cenarion Expedition reputation all the way to Exalted.