There are a lot of platformers in which water equals death, and a lot of platformers that let you swim. Alexander Taylor's Shumping, an entry for Mini Ludum Dare #46, treats water completely differently, however.

In Shumping, you can walk on water. When you land on it, you bounce a little. Pushing down while standing on the water causes you to dive a certain distance. If you jump off the water and time your dive right, though, you can dive deeper. Even though the physics above and below the surface of the water are a clearly different from each other, the way they meet in the middle makes them combine into a cohesive whole that makes for interesting gameplay. Going through a portal flip-flops the physics so that you can fall through water and jump higher in the air.

It was made in 48 hours by one person, so it doesn't have any sound or sophisticated graphics. Limitations breed innovation, though, and the simple look is really quite catching. If you want to check it out, you can go to the Mini LD entry page or play it here.