World 8-1 (New Super Mario Bros. Wii)
From the Super Mario Wiki
World 8-1 is the first level of World 8 in New Super Mario Bros. Wii. It is a volcanic level full of lava, and is the first to feature lava geysers. Volcanic debris falls from the sky and a cloud of ash follows the players from the left to the right.
This level is completely filled with lava. An ash cloud chases Mario from the start to the end of the level, slowly consuming the entire level. If Mario or any of the others touches the cloud, they instantly lose a life. Volcanic debris also falls from the sky, and geysers of lava will erupt periodically from their lava pools. Various metal platforms can be found floating above the lava which slowly sink if stepped on; once Mario and co. are no longer standing atop the platform, it rises back to its original position. Buzzy Beetles are very common in this level, and are the only non-obstacle enemy present.