This level contains many Wigglers and vines. Wigglers are normally peaceful enough, but speed up after being hit. Beware the acid below; it kills with one hit! The floating boxes will support you for a little while, but soon sink, so keep moving!
Star by jumping over the nearby Wiggler and jumping across the first pool of acid. You can jump on the second Wiggler to hit the ? block above and get a Super Leaf. From there, continue leaping from floating box to floating box, collecting red coins along the way if you choose. You will soon see a Wiggler below a floating Star Coin in the air. Jump on it with good timing to get high enough to reach it. Alternatively, Raccoon Mario can glide high enough if he jumps from the top of the nearby hill.
Eventually, after a few more blocks in the acid, you will come across a switch above another Wiggler. Hitting it causes coins to fall out of the pipe to the right. From there, continue right through the red pipe and reach the midpoint flag. Here, the acid occasionally lowers and rises, making this area's geography dynamic. Hit the nearby ? block for another Super Leaf. Jump from box to box, jumping in place if you need to wait for the tide to change in order to ensure a safe jump. Eventually, you will reach an area that is exposed only at low tide. Hurry in and out of there to get the second star coin.
You'll soon see two blocks next to each other. Hit up between them to grow a vine. This leads to a new area with a Gold Ring, a Koopa, and several blocks, allowing for many coins to be collected. At the end is a Super Leaf in a block to collect. Fall down to go back to the main stage. You'll soon see a star coin floating in the air by a wall. Wait until the tide is low, and wall jump to grab it. Then, get back on the nearby box and wait out the tide. Continue moving onward until you reach a green pipe. Go in to reach the flagpole.
Secret Exit[edit]
Just below the final green pipe, there is a red pipe that is only exposed during low tide. Break the wall to it using a koopa shell, and then rush in before the tide rises. A new flagpole will be on the other side.