Wet-Dry World Warp
For this warp, the water level needs to be as low as it can get. Walk around the base of the level until you find the brick structure that is made of several steps. Stand at the base of the structure, in the corner between the highest and lowest steps. The game will warp you to the top of the structure that holds the entrance to the cannon. You can also warp from the cannon to the other structure.