World 5-1, is the twenty-third level of Super Mario 3D Land.
The level begins as Mario lands on the base of a square, rocky mountain. On the base is a Boomerang Flower in a small circular patch of soil, and upon touching said flower, Mario gains the ability to use boomerangs similarly to a Boomerang Bro. At the base are also two Pokeys. On the second level of the mountain is a Boomerang Bro. that when defeated drops a second Boomerang Flower.
At the third level of the mountain, there is a spire that has a large, bent girder on it. Mario must balance on this girder to cross to the other side. Along the narrow slope that follows, two Thwomps jump around, attempting to crush Mario. After the thwomps are two Sandmaarghs guarding the entrance to the inside of the mountain. Once on the inside, Mario finds the Checkpoint of the level.
The inside of the level features a large octagon-shaped panel. Once touched, the piece of land rises up and sand begins to fall from the ceiling. Several obstacles are found on this lift such as Boomerang Bros., Sandmaarghs, and spiked balls. Atop the lift are a few Pokeys and then a cannon that will lead to the level's Flagpole.
- Star Medal 1: By using pristine jumping techniques near the beginning of the level, Mario can find a hidden Warp Pipe leading to the first Star Medal.
- Star Medal 2: On the ledge with the Thwomps, Mario needs to jump atop the Thwomps to obtain the second Star Medal.
- Star Medal 3: The third Star Medal is found inside the mountain. By using the Boomerang power-up, Mario can obtain this coin. This Star Medal can also be obtained by jumping up and using a Tanooki Suit acquired in a separate level to land back onto the platform.
Enemies that appeared in World 5-1: