World 6-4 (New Super Mario Bros.)
From the Super Mario Wiki
This level is a mountain level that has Fire Bars and thin ledges throughout the level. When the first Fire Bar appears, Mario should Wall Jump above it to get the first Star Coin. Mario should then walk across the thin ledges with his back against the wall. To avoid most of the Firebars, Mario should stay down, below the thin ledge. Later, Mario must press a ! Switch to create two blocks that let him advance, or alternatively Wall Jump upward to reach a red Warp Pipe and the midway point. If Mario goes left after this, he will find the second Star Coin. After passing through the red pipe, the player will be in an area filled with thin ledges. Because Mario's jumping is limited, he should only jump when he is close to a lift. When the path splits, the player should take the upper path to reach the final Star Coin. After going through another Warp Pipe, Mario will reach the flagpole.