All the Gopro packages have a water proof case rated to 197 feet that technically can be used for underwater photo's and video's. Gopro does sell a separate "Dive Housing" which has a flat port lens for providing maximum sharpness for your underwater photo's and video's. The housing that comes with the surf unit has a rounded lens which works much better above water giving you a wider field of view. If you will be diving with it or using it underwater I would highly recommend purchasing the upgraded housing Go Pro Dive Housing
its a small upgrade but will make a ton of difference with your underwater photography.