This level takes place in a dark underground cavern. There is a boat with a light that the player can move by rotating the Wii Remote. Various enemies, such as Piranha Plants, Cheep Cheeps, Swoopers, and Fire Bros., make an appearance here. The water may rise or lower at some points of the level.
At the start, slide down the hill to enter the cave below.
When you land on the raft, jump on to the ?-Switch to find it's actually the Tilt Raft. Tilting the Wii Remote sideways changes the direction of the light on the back. The screen will still follow you so feel free to wander off, but the Boat will keep moving, so be weary of that. There are also Cheep-Cheeps in the water that you can't see, so try to swim as little as possible.
There will be some Blocks ahead, along with a Springboard. Get a Fire Flower from the second ? Block and then pick up the SB and bring it back to your watercraft. Drop it near the front. Jump up to some Brick Blocks and climb to some ledges above. Ground Pound the ? Block to drop a Fire Flower on to your raft. Then pick up the POW Block just ahead. Drop back to the Tilt Raft and grab the Fire Flower. Then wait until Star Coin #1 is above the raft and throw the POW Block to get it.
You'll start passing some pipes on the ceiling. Each pipe has a Piranha Plant in it, so watch out. The water will also begin to rise so you start getting closer and closer. After a yellow pipe will be a Brick Block. Hit this Block for a Star which will light up the entire cave when you grab it. Knock out the Plants in the pipes ahead and dive into the water to kill some Cheep-Cheeps for some extra points. After a red pipe the water will suddenly drop to a lower level so you can fit under the wall ahead. Jump to the blue ledges on the other side and run right to the Checkpoint Flag.
Jump to the Coins on the wall when the Tilt Raft gets closer and slide down on to it. Climb the next blue ledges to another Springboard. Bring this one down to your raft as well and sit it towards the back. You should see some yellow eyes glowing in the darkness ahead. These belong to Swoopers, which will make it harder for you to stay aboard your raft. There is a ? Block with and Ice Flower ahead, so take it. Just past here is Star Coin #2 high up near the roof; use a Springboard to reach it.
Jump over some Swoopers ahead and then bounce yourself up to a P-Switch. Grab the Coins but don't stray too far. After the time runs out you should come across a Propeller Block. Bounce up to it and grab it, then drop back to your raft. The four Swoopers ahead will wait until you get between them and then three will swoop at the same time to catch you out, then the fourth after that. Spin Jump in the gap in the middle and float left to dodge them all, then land back on the raft. Spin Jump up through the gap and left just after the Swoopers to land in a tunnel. Run through to Star Coin #3. Head back out and Spin Jump to the tunnel on the other side.
Drop the Propeller Block here and run past the barrel. Stand on the edge of the platform where the fireballs can't get you and throw some ice balls. You should just be able to get the Fire Bro. ahead. Once it's frozen, throw the ice block it's frozen in at the next Fire Bro. to get rid of him.
Jump ahead and dodge the fireballs to freeze the last Fire Bro. If a fireball gets you, run ahead while you can't take more damage and jump on the Bro.'s head. Just past here is the end of the line, so just swim ahead if the raft is a fair way back. Enter the pipe here.
Hit the Brick Blocks for a ?-Switch and hit the Switch to make a moving platform appear. Jump to this platform and then leap to the Finish Flag.
- Cheep Cheeps
- Big Cheep Cheeps
- Piranha Plants
- Fire Bros.
- Star Coin 1: Mario and co. must get the POW Block and activate it while the raft is directly under the four coins to the left of the Green Pipe with the Piranha Plant. This will make the first Star Coin fall onto the raft.
- Star Coin 2: Mario and co. must put the trampoline located shortly after the Checkpoint Flag on the raft and use it to obtain the second Star Coin to the left of three Swoopers.
- Star Coin 3: Mario and co. must obtain the Propeller Block and use it to get into the rock passage directly to the right. The third Star Coin is then all the way to the left.
A secret exit exists in this level which can be found by entering a red pipe in the area with Fire Bros. The player will be in an area with a Glow Block along with a Swooper swarm. After that area is the secret flagpole. This unlocks a Warp Cannon which takes the player to World 8. Players can run through this level with a Mini Mushroom by dashing across the water.