When swimming into a 1 block space, if you look up and keep looking up, you will be able to "stick" to the blocks above you and walk over air. You cannot perform this, however, if you look at any degrees down. When doing this glitch, if you quickly dive into water and look up over empty air, you will slide around as if you are still in water, but if you wait, and then move over the empty space, you will not.