The SteamvaultIntroduced in The Burning Crusade
Coilfang Reservoir is the name for a naga-dominated compound that lurks under Zangarmarsh's deepest waters. The reservoir, punctured throughout by massive open pipes and pistons, seems big enough to house armies - and, yet, its purpose isn't strictly military.
Here, concealed by the cold fathoms, Lady Vashj's naga ply their resources - the exotic flora and fauna of the cavernous Underbog, the Broken who toil in their claustrophobic Slave Pens, and the arcane machinery they've constructed in the Steamvault - towards a catastrophic goal set forth by Illidan the Betrayer. Unopposed, they will drain Zangarmarsh's waters, and claim dominion over the dry bog that remains.