World 4-5 (New Super Mario Bros. 2)
From the Super Mario Wiki
Mario begins on snowy ground where, ironically, a pool of water with a Cheep Cheep exists in front of him which the surface has not frozen in the weather. A green Warp Pipe takes Mario underwater where a Roulette Block can be found at first. Cheep Chomps are common in the level where they frequently chase after Mario. A Cheep Chomp can first be sighted just after the Roulette Block. This is followed by a blue pipe with a strong current which can push Mario further down the level. Many Cheep Cheeps can also be found, some of which have trails of coins behind them. Another blue pipe with current can be found. Further down lies a Coin Roulette Block with another Cheep Chomp. Shortly after is the checkpoint. A ? Block containing a Fire Flower can be found, followed by a Red Ring and a Cheep Chomp. Continuing on is another Cheep Chomp and the second Star Coin. Going upwards and to the right is the last section with several more Cheep Cheeps and a Cheep Chomp, followed by the exit pipe back to the overworld. There is a small pool of water with Cheep Cheeps, followed by a staircase-like hill and the flagpole.