In the Dark World, go to the Village of Outkasts. Where the Bottle Man was in the Light World is a pool of water. Walk right up to the wall surrounding it and warp back to the Light World. When in the Light World, walk up towards the man (he should be right in front of you) and step into the warp point you made from above. If you do it correctly, when you return to the Dark World, you should be inside the pool of water. You can't do anything, but it's cool.
Submitted by: Billy