New Super Mario Bros./World 5

World 5 is one of the four mandatory worlds in the game, and can't be skipped without using a cannon. It has a winter aesthetic, and many of its levels feature ice and snow. There are one of each Toad House in the World, all of them requiring Star Coins to access. This is also the first world that feature Hammer Bros. on the overworld map. Entering a level with a Hammer Bro. patrolling over it will cause you to fight one upon starting the stage.

World 5-2
The secret exit of this level is not particularly hard to get, but not very obvious either. As you go through the stage, keep a lookout for a brick block formation that includes four coins horizontally level above an extension of the formation, also preceded by a Swooper. From this makeshift landmark, go right and get on the ice block. There is a pipe with a Piranha Plant in it at the ceiling above the ice block. Simply jump into the warp pipe when the Piranha Plant is not present to be taken to the red flagpole.

This secret exit opens up a path south into an overworld warp pipe. The warp pipe lets you skip the tower, instead going right to World 5-3.

World 5-Ghost
Near the base of a noticeably steep flight of stairs are a set of three coin blocks. Jump up to bump into three hidden blocks above them. Get on to the middle block then duck and jump (simply jump if you aren't tall Mario) to hit another hidden block. This makes a vine that extends to the ceiling. Climb up until you get to a door behind some blocks. Have the Broozer here break the blocks. It will just barely miss you as it destroy the wall and falls down if you stay on the vine. Go in the door and you'll end up on a lift identical to the one at the end of the main stage. It even moves in exactly the same way. Stick to the right side along the ride, and when it's on its final ascent, quickly move to the opening in the right wall as you pass by it. You can get to the final Star Coin this way. Hit the lone block here to climb to the top of this portion, where the lift would have left you on. Go left and go through the door to arrive at the red flagpole.

This secret exit creates a path to the World 5 Cannon, which blasts you to World 8, Bowser Jr.'s home turf. This is the last cannon in the game, so there's no more major shortcuts from now on!

World 5-B
You must be Shell Mario to access this hidden exit. Near the end of the level, you can see an opening that you can wall jump up, with two coins hinting you to do so. Keep wall jumping up and over the ceiling and go left. Go into a Shell Dash as you run to the left and stay in your shell to break two brick blocks obstructing a narrow tunnel. At the other end of the tunnel is a warp pipe. Go through it to be taken to the red flagpole.

This alternate exit takes you to the second warp pipe in the world. It lets you skip one or two courses as it leaves you just outside the World 5-Castle.

World 5-Castle
Defeat Petey Piranha as Mini Mario. Due to the reduced power of Mini Mario's jump, you need to use Ground Pounds instead to damage him. If you have a Mini Mushroom in reserve, you can enter the fight normally and damage Petey Piranha a few times before using your Mini Mushroom and dealing the final hit. As long as you finish off Petey while in mini form, you have succeeded.

Defeating Petey Piranha unlocks World 7.