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.