Illustration of an infinity pool in a room

Quick answer：

An infinity pool is a type of swimming pool that appears to extend to the horizon, creating an illusion of water flowing off into the distance. This effect is achieved by having the pool's edge at the same level as the surrounding ground or landscape, making the water appear to merge with the environment. In an illustration, the infinity pool would be depicted with a smooth transition from the pool's surface to the natural terrain, often with a view of the horizon line beyond.