A plunge pool is a small pool that is typically used for lounging and cooling off, rather than swimming or activities. It is created by the erosional forces of cascading water on the rocks at the base of a waterfall or shut-in. Plunge pools can be formed by the natural force of falling water, such as at a waterfall or cascade, or they can result from man-made structures such as some spillway designs. They can also be custom-made in your backyard or manufactured off-site. Plunge pools are often very deep, generally related to the height of fall, the volume of water, the resistance of the rock below the pool, and other factors. They can be heated to any temperature you like, and they can be used for aquatic rehabilitation or exercise. Plunge pools are typically smaller than regular pools, measuring 8-12 feet long and wide with a uniform depth of 5-7 feet. They can be built in or above ground and can be customized to various shapes and sizes. Plunge pools can also double as a hot tub in winter and a cool-down pool in the summer if connected to the proper pool machinery.