As the name suggests, the stage takes place underwater. There are six sections, and being underwater will cause all of Kirby's movements to be slow.
- Miniboss: The Blowfish is Section 5 boss
- Shard note: Section 3 will require Rock and Cutter combo
The blowfish is hard to avoid if you are stuck following the current in the Blowfish's opposite direction while trying to inhale enemies to shoot back at him.
- Section two in the middle up against the roof, there is a water current though so if you miss it you won't be able to swim towards it again. Use Rock Cutter combo as the small bird to fly towards it.
- Section three in a water current cave, right near a pole to pass through.
- Section four in another water current, on the floor in a crater.
- In section 3, you must use the Rock and Cutter combo to turn into Pitch (The short round bird). This may take a couple of tries. Fly towards the middle of the roof to see the first Shard.
- In section 4, after traversing some of the current you will see a pole. Travel down it to see the next Shard. You will also need the Rock-Cutter combo so the current doesn’t take you away.
- In section 6, a current will, very quickly, pull you to the end of the stage. Use the Rock-Cutter combo to slow yourself down. Now head to the last bottom ditch. You will see the Shard. If you swim past the Shard, you must reset the level.