World 3-B is the second secret level of World 3 in New Super Mario Bros. The level is accessed by locating the secret exit in World 3-2, and completing the level leads to World 3-C.
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 pole.
- Star Coin 1 - After venturing through some of the level, there should be a lone red pipe. Mario should enter it and then go all the way to the left, and then enter the red pipe in the far left. Mario will be taken to the first Star Coin.
- Star Coin 2 - Mario should Wall Jump on some Warp Pipes to get over a red pipe. Mario should collect the second Star Coin and fall through the small opening in the right side.
- Star Coin 3 - Mario should run past or defeat a Piranha Plant that is in the way of the final Star Coin.