Thanks! .. before we decided what to do we where looking at footage of austronauts in zero-gravity envoriments and the water envoriment was pretty close to that.

I heard and read about the Lytro camera. It sounds super interesting but to really judge how useful it is I would need to see it in action. They claim that you can change the focus/angle (to a certain degree) after the fact. They also claim that the depth information they can capture is so good that you can basically cut out every object at every depth making green/blue-screens obsolete.

I still doubt that you can separate things like fine hair detail and semi transparent objects, and also if, you still would have the problem of colour bleeding from bright objects in the background. But this is just a guess for my side. If I have a chance to work with some actual footage I will let you know!