World 4-5 (New Super Mario Bros.)
From the Super Mario Wiki
This is an underground level with Bob-ombs and platforms that act like drawbridges. Some Brick Blocks can only be destroyed by blowing up a Bob-omb, which is needed for Mario to get past some areas. This skill is also used to get the first Star Coin. To get the second Star Coin, the player must wait until a drawbridge goes up. Next, he must hit the Bob-omb above him, destroying some blocks, allowing him to get the coin. After a few more drawbridges, the player should notice one that has a pipe with blocks covering it. If Mario blows up a Bob-omb on top of the Pipe, he can enter it and, by breaking more blocks with Bob-ombs, he can get the last Star Coin. When Mario leaves the Warp Pipe, he will reach the flagpole.