The problem here was not the water, but the chlorine (and probably urine; the Olympic champions admit that they pee in the pool) in the water. Pentax advertises resistance only to water, not to a chlorine/urine cocktail, and these chemical deposits have damaged the camera. To remove them, you need to thoroughly clean the camera with regular water. Take the lens off and run all parts of the lens under the tap (make sure to zoom and focus the lens aggressively whilst under the tap to break up any deposits!); then do the same for the camera (make sure you the mirror box is washed out well too, as deposits could be lurking there!). If the camera still doesn't work, the deposits have obviously adhered beyond the point of solubility, and you will have to shift them. To do this, use a hammer to strike all portions of the camera and lens. If somehow this fails, then you will have to buy a new hammer.