Watiki Indoor Waterpark 1314 N Elk Vale Road Business City: Rapid City SD 57701 (866) 928-4543 http://www.watikiwaterpark.com/ With 30,000 sq. ft. of pools, slides and splashing fun, WaTiki is the largest indoor waterpark in the Dakotas and one of Rapid City’s best attractions. Hours Mon.-Thurs. 8 a.m.-9 p.m. Fri.-Sat. 8 a.m.-10 p.m. Sun. 8 a.m.-8 p.m.