World 5-1 (Super Mario Bros. 3)

World 5-1 is the first level in Sky Land from Super Mario Bros. 3.

Layout
The player starts in an area with a single Buster Beetle, some bricks, a Wood Block containing a power-up, and a Chain Chomp. If the player has a P-Wing, or is powered-up with a Super Leaf or a Tanooki Suit, they can fly to a Warp Pipe leading to a secret area with a treasure box containing a Music Box, which can be accessed by crouching and flying to a small gap on the right or running across while small, and another Warp Pipe that leads the player to an area below the main level with four 1-Up Mushrooms. Above there are three bricks, one of them with a Switch Block, which makes two numbers (two threes in the NES and SNES versions or a three and a four in the GBA version) made of coins appear. After that, there are some Walking Piranhas, another Buster Beetle and two more Chain Chomps, guarding some ? Blocks, one of them holding a Starman. Afterwards, there are more Walking Piranhas and a Para-Goomba, followed by some bricks and the goal.

Level statistics

 * Power-ups: 3 (Super Mushrooms or Super Leaves and one Starman)
 * 1-Up Mushrooms: 4
 * Secret areas: 1

Trivia

 * In the original Japanese Family Computer release, the main level ends in a pipe, with the goal being in a sublevel. However, because that sublevel also contains the secret area, this leads to a glitch where Mario can trigger the treasure box into appearing. The Nipper Plant and items in the goal box will then appear glitched, and once Mario gets a card, another box spawns in a random spot. If it spawns where Mario can get to it, the "Course Clear! You Got a Card" text also appears glitched. The box contains a fourth Magic Whistle.
 * In the NES and All-Stars versions, it is impossible for Mario to make all four 1-Up Mushrooms spawn at the same time, due to game limitations in the former version. Hitting a block with a second 1-Up Mushroom in it will make the first one disappear. However, Super Mario Advance 4 does allow all four 1-Up Mushrooms to be on-screen at once.
 * Unusually, in the Super Mario All-Stars and Super Mario Advance 4: Super Mario Bros. 3 versions of this level, the Chain Chomps are depicted as having blue mouths.