I like the Y-L swimming controls. Once I figured it out, it became easy enough. I typically don't enjoy swimming in 3D games, but this is something I can dig.
Have you heard of Mushroom Men: The Spore Wars? It was made for the Wii by Red Fly Studios. Its a pretty trippy and fun little 3D platformer. The music was amazing as well. Les Claypool did a lot of the tracks while GL33k did the rest. It did not have a hub or anything, just multiple 3D platformer s...