World 3-B (New Super Mario Bros.)
From the Super Mario Wiki
This level is entirely made up of Warp Pipes. Many of them are inhabited by Piranha Plants and Venus Fire Traps. To begin, Mario just needs to go and jump over the pipes, while avoiding the Venus Fire Trap's fireballs. The first Star Coin is obtained by going into a red Warp Pipe about halfway through the level, then going through another red pipe. Mario then must keep jumping onto more pipes, avoiding all the Piranha Plants. To get the second Star Coin, Mario should Wall Jump between the red and green pipes near the Star Coin, going over the red Warp Pipe. The last Star Coin is obtained easily, just by going past a Piranha Plant. After the Star Coin is the flagpole.