World 5-Fortress 2

 2 is the second fortress and tenth overall level of Sky Land in Super Mario Bros. 3. It is the first and only fortress found in the sky portion of the world. This level can be played upon the completion of either World 5-6 or World 5-7.

Level layout
This level spawns Mario on a two block platform floating above a lava pit. To his right is a single block and another gap that leads to a gray Warp Pipe. This Warp Pipe takes Mario down to a lower floor of the fortress, where the ceiling, as well as the floor, is covered in lava. Lava Bubbles constantly launch from above and below Mario. Mario must make his way over a few gaps and platforms until he gets to a long platform that has six connected ? Blocks. The last block produces a Super Star when hit. Past these blocks, a Dry Bones encounters Mario. Mario then must hop over a few more gaps and short platforms. A platform low to the ground has a Boo to the left of it. Past this platform are two one block-wide bridges that Mario must hop across in order to reach another longer platform with two ? Blocks. The block on the left produces a Super Mushroom or Super Leaf when hit. After this platform, there is a final gap that leads to a longer platform. Numerous Lava Bubbles jump towards this platform and a Boo can be found in the middle of it. At the end of the platform is another Dry Bones walking beneath a Warp Pipe. This Warp Pipe transports Mario up to a higher floor. He must clear one more gap of lava to enter the final room to fight Boom Boom.

Enemies

 * Lava Bubbles
 * Dry Bones
 * Boos
 * Boom Boom (boss)

Level statistics

 * Power-ups: 2 (Super Star, and Super Mushroom or Super Leaf)
 * 1-Up Mushrooms: 0
 * Secret areas: 0