Steamvault

The Steamvault (also known as the Steam Vaults) is the level 70 wing of the Coilfang Reservoir. No key is required to enter. You must defeat the first and second bosses and operate the control panels behind them in order to enter the room with the final boss.

Background
The Steam Vaults serves as the mechanical heart of Naga's draining operations in Zangarmarsh. The mechanisms on display within the massive cavern supply the power for the actual act of removing the marsh's water. As a result, the Steam Vaults is perhaps the most strategically important wing of the Coilfang Reservoir for adventurers looking to put a stop to Lady Vashj's efforts.

Dungeon Journal
''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.''

Quests

 * Storming the Steamvault
 * The Warlord's Hideout
 * Underworld Loam
 * Windcaller Claw and the Water Thief
 * WANTED: Coilfang Myrmidons
 * WANTED: The Warlord's Treatise
 * The Second and Third Fragments
 * Containment is Key
 * A Proper Fate
 * Trial of the Naaru: Strength

Removed quests

 * The Warlord's Hideout Given by Watcher Jhang at the entrance to Coilfang Reservoir.
 * Orders from Lady Vashj (quest) Starts with a random drop of the same name inside the instance.
 * Preparing for War (quest) The repeatable follow-up to turn in Coilfang Armaments.
 * The Second and Third Fragments Given by Khadgar at the Terrace of Light in Shattrath City, this is step 6 in a quest chain to obtain the Master's Key that starts with Archmage Alturus at the entrance to Karazhan in Deadwind Pass.  The Second Key Fragment is found in this instance. It can be located in the water just in front of the first boss Hydromancer Thespia.  This key fragment may be obtained without killing the first boss if simply obtaining the key is your goal.  A direct route to the key requires clearing mobs while hugging the right wall from the start of the instance, take a hard right and up the ramp, and clear enough space to be able to jump into the water.  Dive into the water at the leading edge of the bridge and search the pond for the key giver.  The key may be obtained with six or seven pulls from the start of the instance. This instance no longer requires a key to open the door inside.  There are now panels behind each of the bosses that need to be activated - this will automatically unlock the door.

Achievements

 * The Steamvault (achievement)
 * Heroic: The Steamvault
 * Heroic: The Steamvault Guild Run

Reputation
All mobs give Reputation to Cenarion Expedition through Exalted. Rep Given: Trash: 12, 2 (non-elite), Bosses: 120, Full clear 1,662 rep. (1,782 if you take the time to kill all of the slaves as well.) The fastest path through the instance nets ~1100 rep. In Heroic Mode, the fastest path gives roughly 1550 rep, and a full clear will give 2,559 rep.