New Super Mario Bros. U: Sparkling Waters-2 -- Tropical Refresher

This level starts outside, but you'll take the pipe to an underwater level. There are Cheep-Cheep and Bloopers here, as well as Urchins. Many of the pipes have currents, and some of the pipes move. Arcs of coins appear from some red pipes, then disappear. Under the first Urchin is a Red Coin Ring in an invisible area. The first Star Coin appears along a set of three pipes. It will appear along the pipes, then disappear into the void, then reappear. Past the giant Urchin is the midpoint. There are two giant Urchins over a vortex with a rock in it. Between them is an invisible ? Switch which makes coins appear from above, including the second Star Coin. There's a green pipe under an Urchin, which leads to a Starman. Quickly return to the main level and go down the next green pipe. While you still have the power, drop down and kill the giant Urchin. Below it is the third Star Coin over a vortex. Follow the Cheep-Cheep to the pipe to the flagpole. This opens the path to a 1-up Mushroom House and the Fort.