It is unlocked by completing World 3-. This course is unique in that it must be played through twice in order to progress in the game.
The first time this level is played, the only accessible exit is a secret exit which unlocks World 3-5 and a red Toad House. After completing World 3-5, the player gains access to a ! Switch. There are Dotted-Line Blocks in Worlds 3-4 and 3-5 which turn into solid Red Blocks when this switch is activated. The course must then be played through again, with the Red Blocks allowing access to an underground path leading to the "regular" exit, which unlocks World 3-.
The player starts on an ice platform with a moving ice block in front of them. A Penguin Suit is obtainable from one of the ? Blocks. The player then meets a red Koopa Troopa and another moving ice block. Further down, there is another moving ice block with a Fire Bro. A smaller moving ice block follows, then two large ice blocks with ice platforms and red Koopa Paratroopas. The midway point follows, where the player finds two Goombas. This is followed by six fast-moving ice blocks with narrow ice platforms and another red Koopa Troopa. There are two paths from this area depending on whether the ! Switch has been activated.
First Exit ("Secret Exit")
This exit is represented by the red flag used for secret exits throughout the game and is the only exit available before the ! Switch is activated. To the right of the the six moving ice blocks is a Roulette Block, followed by more moving ice blocks which obstruct the players' path. Two Fire Bros. also try to prevent the player from progressing. Just before the flagpole is a POW Block, more Koopa Troopas and a large moving ice block. The POW Block causes hidden coins to fall onto the moving ice block. This exit unlocks World 3-5 and a Red Toad House.
Second Exit ("Normal Exit")
This exit is only accessible after activating the ! Switch on the World 3 Map. Below the six moving ice blocks is a line of red blocks that can safely be crossed. The player can continue to a red Warp Pipe which leads underground. The players can cross platforms of red blocks and ice blocks which can be thrown to collect coins and attack Goombas. Another red pipe leads back to the surface and the flagpole. This exit unlocks World 3-Castle.
- Star Coin 1: The first Star Coin is floating in plain sight over the first Fire Bro.
- Star Coin 2: The second Star Coin is located in the area with several glacier rides, inside a hidden area under a mid-air platform. Mario and co. should get on the second one, duck, then jump to get the Star Coin.
- Star Coin 3: The third Star Coin is in the area from which infinite glacier rides emerge. Mario and co. must traverse across the many glacier rides while avoiding the Fire Bros to get the Star Coin.
- The Prima Guide map for this level marks the secret exit as a normal exit and the normal exit as a secret exit.