Wario Land 3: Part 32: The Tidal Coast (Red Chest)

There's a warp pipe guarded by enemy blocks that you can break through. In the next room, you must swim toward the red key, avoiding bubbles and using them to push through water currents. Then return down a different doorway, go up to the dry part of the room, and reach the red chest. The chest contains the Foot of Stone. Wario tosses it into the air, crashes it to the ground, and its earthshaking stomp creates new openings for The Volcano's Base and The Steep Canyon, and drains The Stagnant Swamp.