I've bought an underwater housing for a P&S from this supplier based in the UK:


http://www.camerasunderwater.co.uk/index.html


Check out their website to give yourself an idea of whats available out there. I have also found that you'll need to put a satchet of silica gel into any housing with the camera to prevent fogging, especially if you're in a very humid environment - its surprising the amount of moistue that ends up trapped inside!