|Stage Subtype||Order of No Quarter|
|Theme||A Thousand Leagues Below|
|SoT Theme||The Price of Doing Business|
|Unlockable Curio||Hover Plume|
The Iron Whale itself is a large whale-shaped submarine filled with floating platforms, spikes and dangerous fauna. Most of the stage takes place underwater, with the water resistance increasing jumps while making falls slower. Half of its exploration is inside the submarine, while the rest takes place in the dark depths beneath it. Those underwater grottoes are filled with hostile fauna as well as the hunting grounds of Teethalon. The last section is filled with anchors and torpedo launchers. Treasure Knight guards his vault, full to the brim with gold.
In Shovel of Hope and Plague of Shadows, the Iron Whale is submerged, leaving few parts outside water. In Specter of Torment, Treasure Knight brought his vessel topside. The nearby coast is visited while the submarine is half-submerged inside.
Treasure Knight used the Iron Whale to plunder the sunken wrecks around the Valley's sea. Specter Knight intruded the ship to recruit him into the Order of No Quarter. After this, the Iron Whale served both as impregnable treasury to the army of the Enchantress and vessel to patrol the sea.
Shovel Knight or Plague Knight later infiltrated the ship to face the greedy deep sea adventurer. After the Order's defeat, Treasure Knight's entire ill-gotten fortune was reclaimed by the Valley's locals, much to his despair.
- Grey Hermittack
- Purple Goldarmor
- Gulper Mage
- Lunkeroth (SoT)