Most water rides are designed to get your guests wet. They run the gamut from cute little rowboat rides to intense water slides that can rival your roller coasters in popularity and profitability. All water rides involve custom designs, although some are as simple as building a station.
Note that in RCT1, to research water rides, the "Thrill Rides" option must be checked. In the other two games, "Water Rides" is its own option.
(Note: In RCT3 Log flumes, Dingy/Water slides, Water Coaster ect, are considered roller coasters, to find these, toggle off wooden coasters,steel,and inverted coasters. Gentle water rides will be under the water ride section, and pool slides have their own section.)