A swimming pool, swimming bath, wading pool, paddling pool (or simply a pool), is a man-made container filled with water intended for swimming or other water-basedrecreation. A pool can be built either above or in-ground, and be constructed from materials such as concrete (also known as gunite), metal, plastic or fiberglass. Pools can be decorative or custom shape and size, or they may be standard sizes, the largest of which is the Olympic-size swimming pool.