World Star-6 (New Super Mario Bros. 2)
From the Super Mario Wiki
The level begins on a small emerged area of the fort, with a ghostly background and three Brick Blocks. To the far right there is a vertical passage with coins, leading to an underwater fort where Mario must reach a Warp Pipe avoiding Fishbones. This pipe leads Mario to a horizontal, auto-scrolling corridor, where he can find a ? Block containing a Super Leaf and a Fishbone. Some Fishbones and coins over a pit are then found, followed by a passage containing more Fishbones in it. After a pit where coins in bubbles are found, Mario encounters a group of six Fishbones. The Checkpoint Flag is then found, along with two Brick Blocks, one of which contains a Fire Flower. Mario must then travel up, where he encounters Fishbones and an ! Pipe that produces three 1-Up Mushrooms. The level then moves horizontal again, and a Roulette Block and some groups of Brick Blocks are found. Blue Warp Pipes blowing bubbles are then found, along with a Red Ring. After another group of Fishbones, Mario reaches the end of the passage, where there is another Warp Pipe leading to the Goal Pole area.