This is just a frame so quite expensive at $759. Have a look too at the build guide and video. I doubt if it could handle more than sea state 1.
http://www.quadh2o.com/ (http://www.quadh2o.com/)
http://www.quadh2o.com/resources/the-quadh2o-build-guide/ (http://www.quadh2o.com/resources/the-quadh2o-build-guide/)
The amazing QuadH2o™ Quadcopter landing on water (http://www.youtube.com/watch?v=Bls8oI8NvnQ#ws)
Why do they put the whole body in the water - if they put some plastic booms underneath it could probably handle a bit of choppy water, but any sign of a wave at the moment is going to swamp the props and stop you from lifting off again.
I'm thinking along the lines of those heli-trainer struts with the balls on the ends.
(http://www.bananahobby.com/images_templ/trainingImage/img13.jpg)
But obviously with a lot more surface area for buoyancy.
I just would so much like a flying sub like the Voyage to the bottom of the sea had :D sigh ;)
dizzy ;)