I am talking about floating about a foot off the ground, not floating in water.
At first I thought this would be just a feature (something to make a wizard or psychic look cool), but simply not touching the ground makes this character immune to any attacks that require them to touch the ground, as well as Tremorsense (ranged tough, along the ground), and they are immune to being slowed down by terrain or being tracked by scent, etc... That is probably be worth more than one point.
The other ideas was a very Limited Flight (perhaps rank 0, because the character moves at only 2 miles per hour, and in any event Limited to only one foot or so off the ground... and Subtle). Flight already grants the other required abilities (immunity to Tremorsense, earthquakes, being slowed by terrain or being tracked). It wouldn't allow Water-Walking since it's basically projecting just enough force downward to lift the character above the ground.
I thought of two ways to handle the same ability, and of course there may be other ways of handling this that I haven't thought of. Any pointers?