The Reef Indoor Waterpark brings slides, a wave pool, and warm-water play to Billings, which can be useful in a city where weather swings hard between seasons. It is attached to a hotel complex but functions as a family attraction in its own right, especially for children who need activity after long drives across Montana.
This is not a cultural highlight of Billings, but it clears the practical travel test: on a cold, windy, or smoky day, it gives families a reliable indoor option. Check public admission rules before going, as access and hours can vary around hotel and event use.