World 8-5 (New Super Mario Bros.)
From the Super Mario Wiki
This level takes place around a volcano. There is a lot of lava, as well as unstable platforms that fall if Mario stands on them for too long. Lava Bubbles jump out of the lava, and generic enemies (such as Goombas and Koopa Troopas) also appear in the level. Since this level is relatively short, there is no checkpoint.