Super Mario 3D World: 3-Toad -- Captain Toad Makes a Splash

Time for adventure! Captain Toad finds himself in a water level. There's a spiky hammerhead shark swimming around. Walk underwater to find the first Green Star behind the hammerhead. While underwater, walk to the other side of the wall through one of the gaps. There's a clear pipe there. Take the pipe to the far right area and walk through the gap for the second Green Star. Take the pipe to the left area and walk on the planks on the other side of the wall. It will take you back to the side with the clear pipe. Drop down into the water and walk on the planks on the side of the wall with the hammerhead. Get the third Green Star at the edge of the plank, then keep walking forward and drop into the clear pipe. This will take you to the top of the wall. Walk across the top of the wall until you fall through a grate. You'll land on a P-Switch, which makes the water level and planks rise. Drop down to the planks and walk to the fourth Green Star. The planks lead you to a ramp up the wall to the fifth Green Star.

New Super Mario Bros.: 1-A

We need 5 Star Coins to unlock this level, but it gives us an opportunity to save. It's an underwater level that is also an automatic sidescroller. There are sharks that will periodically appear and swim by, so don't swim around the right edge of the screen. Further along are yellow bouncy spheres that will push you around, making the area a little difficult to navigate. There's a P-Switch that will make lots of silver coins appear between the spheres. The first Star Coin is soon after, but some invisible blocks will make getting it a little difficult. There is a green pipe nearby that takes us to the second Star Coin. There is a Red Coin Ring before it. We get a much-needed Fire Flower from it, which we can use to take out the sharks. At the midpoint, we get a Starman from a random item block and take out some sharks. Next are some pipes creating currents that can push you into sharks if you're not careful. The third Star Coin is past a yellow pipe. It's near the ceiling. You can get it from the left side if you're small, or go around the right side. Soon after is the pipe to the flagpole. This opens up a path to the castle.