New Super Mario Bros. U: Soda Jungle- Airship -- The Mighty Cannonship

Once you leave either Frosted Glacier or Sparkling Waters for the first time after clearing the castle, you'll come across this lone spot where the Bowser Airship flies in and picks up Mario. There are Mecha Koopas on board. Cannons fire cannonballs at you while the level automatically sidescrolls. There are screws you'll have to jump on repeatedly to make them move. There are stacks of crates you can pound, and if you quickly go down a rope ladder, you'll find the first Star Coin. After the first Star Coin is a Red Coin Ring, as well as another screw. Bounce off of a cannonball to reach the second Star Coin high in the air. Past the midpoint is a red pipe that takes you underwater, where you'll find Mecha Cheep-Cheep and red, homing Torpedo Teds. The third Star Coin is surrounded by brick blocks, so either be at least Super Mario to break the bricks, or let Torpedo Ted break them for you. Go down the red pipe that the sign with the arrow is pointing to, and that leads you to a room with Bowser Jr. in a Clown Submarine. The room fills with water and Bowser Jr. fires red Torpedo Teds at you. Lead the Torpedo Teds into the submarine for a hit. Bowser Jr. will then send a wave of regular Torpedo Teds at you from the sides, so stay out of their way. After hitting him a second time, the regular Torpedo Teds will appear from the floor and ceiling. After the third hit, the water drains from the room. Bowser Jr. hops into the Clown Copter and the Airship's hand appears to swipe Mario away. Mario dodges the hand and leaves the Airship, watching it fly away. We can now save our game. This opens the path to Soda Jungle-1.