World 3-B is a level found in the game New Super Mario Bros. It is unlocked when finding the secret exit in World 3-2. It unlocks World 3-C upon completion. You can also buy a 1-UP Mushroom House upon completion.
When Mario first spawns in, a Piranha Plant will be in the first green pipe sticking out. Next, will be a yellow pipe with another Piranha Plant and some coins. Then there will be the first 2 question blocks with one having a power-up. Next is an area with pipes coming from above and below having lots of Piranha Plants and also the first Venus Fire Traps. At the end is another question block having another power-up. After this is more question blocks with coins and then the first Star Coin can be seen under some blocks in between some green pipes. You won't be able to get it, but if you keep going and then go down the next red warp pipe, you will be in an area with more Piranha Plants and a roulette block. Go up the red pipe in between the two green pipes with Piranha Plants and it will take you underneath the blocks to the first Star Coin. Once you get past all the Piranha Plants and Venus Fire Traps, you will reach the checkpoint and two more question blocks with another power-up. The second Star Coin will be seen above but the only way to obtain it is to wall jump between the red and green pipes and then exit through the small hole to the right. Next will be four-way pipes with Piranha Plants coming out in different directions. After that will be the last Star Coin under a pipe, however being guarded by many Piranha Plants. It may be easier to kill the Piranha Plant on top and then get the Star Coin from the left. After this will be a red pipe with Piranha Plants coming out of both ends and then Mario can slide down the flagpole.
- 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 on 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.