World 2-2 is the second level of World 2 in Super Mario Bros. This is the first underwater level in the game, and in turn, the first underwater level of the series.
The player starts with their character walking into a Warp Pipe, which will take them to the underwater portion of the level.
In order to move around in the water, the player needs to press the jump button to propel themselves upward. The player can also walk along the waterbed, but their movement will be slowed. In the water are many Bloopers and Cheep Cheeps that swim around, with Bloopers moving toward the player and the Cheep Cheeps swimming across the screen. Both enemies can also move through platforms and walls. In three locations in the level are areas with strong currents that will pull the player downward, so the player needs to rapidly swim in order to escape; if the player goes too far down, they will lose a life. The Warp Pipe at the end of the stage will take the player to the Goal Pole, where a Piranha Plant can be found in the pipe the player exited from.