World 8-8 (New Super Mario Bros.)
From the Super Mario Wiki, the Mario encyclopedia
The level begins on flat ground, with the volcanoes in the background erupting and debris beginning to rain down almost immediately. There are some Hard Blocks in the area that the debris will break through, and Kab-ombs that will light up and chase after the player after coming in contact with debris (or with a fireball from Fire Mario). This sort of expanse continues within the level until the midway point is reached, with occasional gaps in between. Just before the midway point is a one-way platform with a mini Warp Pipe underneath; there is a Hidden Block containing a Starman located here.
After the midway point, there are some gaps with Hard Blocks covering them. The ground steadily rises until it reaches a row of nothing but Hard Blocks; with the debris breaking the blocks and the multiple Kab-ombs in the area, this section is rather hazardous. After making it through the row of Hard Blocks, the flagpole will be reached, allowing the players to access the second-to-last level of the game.