A guide to completing the second World 3 Fortress in Super Mario Bros 3 for the Nintendo Entertainment System.

How to Clear the Fortress

Much of this fortress is underwater, so the Frog Suit is a good choice for this level.

Go to the right and get in the water, and go down the pipe.

Go to the right, and there is a Roto-Disc to dodge. After that, there is a Green Cheep-Cheep (which looks a bit blue) in the upper part of the screen, followed by a ? Block in the middle of the screen that contains a Super Mushroom or Fire Flower (but you might not want to get it if you're using the Frog Suit), then a Green Cheep-Cheep in the lower part of the screen.

Then there is one more Roto-Disc, and a Green Cheep-Cheep, followed by a pipe. Go down the pipe.

Go to the right and you find some white bars with Stretches (a type of Boo ghost) sticking their heads up and moving back and forth. Stretches can't leave the platform that they're stuck to, so just keep your distance.

Keep going to the right to reach a pipe. Go down it.

Boom Boom

Go to the right and you find the fortress boss, Boom Boom. This time, there are a couple of blue blocks that you can jump up onto if needed. He will move left and right, and sometimes he will crouch and slide. Whenever he crouches, his spiky shell is not safe to stomp on. Try to stomp on him when he is running around. You can also hit him with fireballs. After you stomp him the first time, he will start flying in the air, going left and right, then he sometimes stops and tries to swoop down at you. Try to stomp him when he swoops down. After you stomp on him a second time, he will very quickly run left and right, so jump carefully to avoid letting him bump into you.

After you stomp him a third time, he is defeated, and drops a Magic Ball. Collect it and you will complete the level.

After the Level

The locked door will disappear, giving you access to a Warp Pipe, which just leads back to the earlier part of the world.

You can optionally go to the Spade House to play the slot machine game.

Then you can go to World 3-8. If you get at least 44 coins in World 3-8, a White Mushroom House will appear, where you will get a P Wing.