New Super Mario Bros.: 8-3

A pipe takes us underwater where large yellow bubbles bounce us around. Swim up to find Unagi swimming around or hanging out in rocks. There are some Red Coins partway up and at the top, you'll reach the midpoint. Here, you'll be chased by a giant Unagi. Do not stop swimming. If you do, the Unagi will drop down on you or rise up to damage you. It is completely invincible. All the Starman can do is prevent you from taking damage. The pipes have currents to push you along to the right. At the end of a long chain of blocks is a Starman. The P-Switch makes Silver Coins. Stay low to reach the first Star Coin. Be Super Mario to take out the bricks guarding the second Star Coin at the top. There are more Red Coins. Stay low over a green pipe with a current to reach the third Star Coin. At the end are two pipes: red and green. Take either to the flagpole.