Visit the Water Park at Bohrer Park if you're in western Montgomery or Frederick counties. This Gaithersburg swimming complex features a large pool, water slides, tot pool, water umbrella, fountain and sprays. It is operated by the City of Gaithersburg so the cost is quite reasonable, particularly for city residents.
Purchase a ticket to Six Flags America to enjoy the Hurricane Harbor Water Park that comes with admission to the park. Thrill rides include the Tornado (a giant funnel down that riders slide on inner tubes) and Tony Hawk's Halfpipe (a water slide promising speeds of up to 23 miles per hour). Non-thrill seekers may enjoy the Hurricane Bay wave pool and Castaway Creek lazy river ride.
Check out Chesapeake Beach's Water Park. This is another city owned and operated facility, this one in Calvert County. It offers eight different water slides, a lazy river, a lap pool, a children's pool and a number of fountains and sprinklers.
Whoop it up at the wild west-themed Frontier Town on Maryland's eastern shore. In addition to the lazy river, water slides and cactus-shaped fountains, you can also enjoy miniature golf, arcade games and a wild west show.
Take a break from the beach at the Jolly Roger's Splash Mountain in Ocean City, the largest water park on the Delmarva peninsula. Rides include the Tower Tube flume and Master Blaster water roller coaster. Other attractions include a waterfall bubble pool and a 1,000-foot-long lazy river.