Swimming in the Ak'Anon Waterfall
 

You can enter the waterfall near the Priest of Discord in Ak'Anon simply by walking into it from the path. If you swim up into the waterfall, and then try to swim out of the "wall" of the waterfall, you'll likely end up with your camera and controls getting discombobulated in such an unintuitive fashion that you will probably drown before regaining control.