New Super Mario Bros. U: Soda Jungle- Fort -- Snake Block Tower

Go through the pipe in the first room to reach a giant snake block, which will take you through the first part of the fort. There are spike balls on spiked chains and Amps, so watch your step. The first Star Coin is near the second Amp you'll see. There are Red Coins to collect, and a nearby small snake block that leads to the second Star Coin. Be sure to quickly return to the large snake block, because the small snake block will pass through the walls without you, leaving you to fall. The large snake block will take you to the midpoint. There's a gap overhead that leads to a pipe. This leads to the next part of the fort. You can get the Acorn Mushroom here and you'll have to follow the large snake block. The small snake block on the right will take you to the third Star Coin. This part of the fort has larger balls and chains, so duck when they get close. The large snake block will take you to the boss door, where there's an invisible item block on the left wall. Once through the boss door, Kamek appears and makes Boom Boom larger, so he can jump higher. Defeat him as you normally do to open the path deeper into the forest, where things transition. The level that opens up is the Ghost House.