World 9-2 (Super Mario Bros.: The Lost Levels)
From the Super Mario Wiki, the Mario encyclopedia
World 9-2 is the second level of World 9 in Super Mario Bros.: The Lost Levels. Like the previous level, it uses overworld tiles underwater, which in the original, leads to many graphics appearing with unusual colors, due to many secondary tiles using the same palette as the coral tiles.
This level takes place entirely underwater. There are many pipes with Piranha Plants situated over a large chasm, with Lakitu traveling along the center of the stage until the player reaches the Goal Pole. From halfway through the level to the end, there are additional platforms with pipes and Coins.