25C (77 F) is pretty cold. Olympic pools are not allowed to be below 25C as the cold water would effect performance. Anything below 70F is considered dangerous. Especially kids would find 25C to be uncomfortable since they don't usually have a lot of insulating body fat.

You could refer them to this website:

National Center for Cold Water Safety - What is Cold Water?

There is an interesting graphic on the side which compares water to air temps. 25C is comfortable air temp but an unacceptable water temp for a hotel pool, IMO.