World 6-1 (New Super Mario Bros. 2)
From the Super Mario Wiki
World 6-1 is the first level of World 6. This level contains Volcanic debris and POW Blocks. The volcanic debris can easily destroy platforms the player can stand on, as well as blocks that contain power-ups and coins.
The player must either hit the POW Blocks to get coins faster from Brick Blocks or let the debris hit it. Then the player should continue and more volcanic debris falls. After the Checkpoint, the player must hit a switch, and then go up a bridge quickly, as the volcanic debris smashes the bridge. The second Star Coin is trapped at the end of the bridge surrounded by bricks. To get it, the volcanic debris must hit it. The player must then get it before the debris smashes the ground. After this is the Goal Pole.