World 3-1 (Super Mario Bros. 3)
From the Super Mario Wiki, the Mario encyclopedia
The level begins in an underwater area with Bloobers and pipes producing current, and falling through the chasm to the left will bring the player to a power-up. To the left of the first set of pipes and sinking downward, the player will pass a few more Bloobers and two Lava Lotuses before swimming back upward, though the player can also jump over the pipe above the water to reach a hidden power-up. The next area splits into an upper and lower section, with the upper section having a Scattering Bloober and the lower having many Jump Blocks that can bounce the player around near a Lava Lotus before reaching a 1-Up Mushroom surrounded by coins. One last Bloober waits before the Warp Pipe leading to the goal.