World 5-5 (New Super Mario Bros. Wii)
From the Super Mario Wiki
The player first jumps on one of the backs of a giant green Jumbo Ray. They have platforms to help them just in case they lose a Jumbo Ray. There are also Propeller Blocks that help them. There are a lot of Bullet Bills in the level that are fired at the player from off-screen. After halfway, the player continues jumping on Jumbo Rays and avoiding Bullet Bills. Near the end, they can travel through a Warp Pipe that takes them to the flagpole, where the level ends.