New Super Mario Bros. U: Layer-Cake Desert-3 -- Fire Snake Cavern

It's another underground level. Grab the Ice Flower outside and take the pipe underground. This cavern is dark, but has a few lights in it. There are lots of Fire Snakes in the cavern, but the Ice Flower can extinguish them. Some of the lights in the cavern are attached to tilting platforms. The second set of tilting platforms will allow you to reach a high ledge with the first Star Coin. Making life difficult while providing some illumination are the occasional Fire Piranhas. In an item block is a Yellow Baby Yoshi, which glows for better visibility. It also eats most enemies, including the Fire Snakes. It can't eat Fire Bros, which appear before the midpoint. There's a low pipe which will take you to a 1-up and some Piranha Plants. There's a Red Coin Ring nearby. The next set of tilting platforms has brick blocks in it. Break them to reach a pipe below. It takes you to the second Star Coin. Afterwards are more Fire Snakes and a P-Switch. Soon, you'll come to some more tilting platforms with Fire Bros. Over the first Fire Bro is a pipe to the third Star Coin. Afterwards, continue to the right, take a pipe above ground and go to the flagpole. This opens the path to the Fort.