Fifteen minutes north of downtown Denver, Water World claims it has the largest number of attractions, 42, of any outdoor water park in the United States. Preschoolers frolic on slides at Wally World or in the FunHouse, school-age children master the tube rides at River Country, while thrill-seeking teens hurl down the Bermuda Triangle body slides and Zoomerang’s half pipe. You can bring life-jackets for your non-swimmers, but they must be U.S. Coast Guard approved; you can also borrow life jackets on site. One nice perk: feel free to bring coolers (no glass or alcohol) inside the grounds; avoid pricey items from the on-site restaurants, and pack your own sandwiches, drinks and treats to eat at the picnic pavilions throughout the park. Generally open Memorial Day through mid-August daily, then weekends through Labor Day.