New Super Mario Bros. U: Frosted Glacier-5 -- Icicle Caverns

Time to deal with more icicles. A large icicle will drop from the ceiling so you can reach the pipe. This leads to an underground cave with icicles. You'll get the Fire Flower in this level, which is completely useless against the Buzzy Beetles. After a set of yellow verertically-moving platforms, you find a set of brick blocks. Above it is an invisible block, which allows you to go up and over the ceiling for some coins. There is an invisible area to the right of where one of the large icicles will fall. The large icicle will block your access to it, so move quickly. The first Star Coin is there. Dodge the icicles and you'll see a Red Coin Ring. The midpoint is after that. Over a set of brick blocks is an Ice Bro. There's a pipe over it, which leads to the second Star Coin. If you're having difficulty reaching the pipe, use an Acorn Mushroom. The second Star Coin is between two large icicles. Towards the end, there will be small icicles, as well as a series of large ones leading to the end pipe. If you're quick enough, you can slip under the last large icicle and reach a different pipe, which will allow you to reach the third Star Coin, which is up in the air. Both pipes lead to the same goal. This opens the path to the Ghost House.