Yes, I know exactly what you mean by "floaty" feeling.
I feel this way often... almost as if my feet aren't touching the ground, and like I'm in a tunnel (vision gets kind of weird).
When I feel this way, I've learned to concentrate on how I'm breathing. If I am breathing through my chest (instead of lower belly), it could be the carbon dioxide. Sometimes I even breathe into a paper bag for about 5 minutes until the feeling goes away.
I HATE that feeling..for me, it is probably the worst symptom of my anxiety/panic attacks but I am working VERY hard to not concentrate on it when it comes and to overcome it.