Why is everybody gushing about water parks? Because they not only provide cool relief on a summer day, but they also combine the thrills of an amusement park with the relaxation of a day at the pool. In the 20 years since the first parks opened, these watery playgrounds have become enormously popular–last year more than 58 million people visited one. Bigger and better than ever, the parks lure families with dozens of slick attractions, from towering slides and twisting chutes to gadget-filled pirate ships and rollicking wave pools. They also offer picnic spots, plenty of lounge chairs, locker rentals and food service. The following parks are some of the country’s best, so pack your swimsuits, towels and sunscreen and go soak up the fun.