World 6-Fortress 2

 2 is the second fortress in Ice Land from Super Mario Bros. 3, and the ninth level in the world overall.

Layout
This level is a very simple level made mostly from Ice Blocks. It starts with a sliding Thwomp, a Boo, and a ? Block with a Super Leaf. Next, there are three more sliding Thwomps before a second ? Block with another Super Leaf. Next, there a few Roto-discs, three more sliding Thwomps, another Boo, and a Warp Door which takes Mario to the boss - Boom Boom.

Enemies

 * Thwomps
 * Boos
 * Roto-discs
 * Boom Boom (boss)

Level statistics

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

Trivia

 * ? Blocks in 2 appear with black question marks instead of white in the original Nintendo Entertainment System release.