The rink is the playing area for the game of hockey. In the NHL, the official rink size is 85 by 200 feet. These dimensions are based on the size of the Victoria Skating Rink in Montreal, Canada. NHL Rinks are considered to be "artificial ice rinks" meaning they are not frozen naturally.
An NHL rink is built on a sand or concrete based on which pipes are laid. These pipes carry a salt brine fluid, refrigerant, or a mix of water and antifreeze. All three of these fluids cause the temperature of the water poured over the pipes to freeze rapidly and stay frozen, providing the surface of the ice rink. A "natural" ice rink is one where water is poured onto a flat surface surrounded by a short edge to contain the water. The natural air temperature where the water is poured must be cold enough to cause the water to freeze on its own, without using artificial means.