Is it correct to use water pool instead of swimming pool? In some hotel descriptions I have found water pool, but it looks like it was a mistake.
Hotels can typically invent creative names for their facilities -- no grammatical/ literary oversight needed.
A water pool is just that, a pool of water. A swimming pool is a pool of water specially designated for the purpose of swimming.
It is not common to refer to a swimming pool as a water pool at all.
One plausibility, however, is: A suitable pool of water where swimming is allowed, such as part of a lake (esp. in rural areas). It is quite common for people to swim in natural pools of water regularly used for the purpose.
Swimming pool is a container filled with water for the purpose of swimming or other water based recreations. Water pool also the means the same but its scarcely used. Its not a mistake they just wanted to put it in a different way probably.
I believe that they use water pool to pre-warn guests that it is not a pool for althletic training like swimming laps.
Just as you would say "wading pool" if it was 1' deep, not "swimming pool."