Among the 10 wildest water parks in America is Schlitterbahn, where one of the highlights is the Master Blaster water coaster—its uphill water-propelled technology (patented by Schlitterbahn) has been adopted by 100 water parks worldwide. The New Braunfels park also hosts the world's first surfing machine, Boogie Bahn. Schlitterbahn (German for "slippery road") operates three water parks in Texas and is opening a resort in Kansas City, Kan., next summer that will include a saltwater marine park for diving, miles of tubing waterways, and its own Master Blaster. But New Braunfels—on the site of the spring-fed Comal River—is Schlitterbahn's flagship Bavarian-themed water park. With more than 40 rides, the park introduced another full-immersion ride on Memorial Day weekend: The Dragon's Revenge.

At Mt. Olympus, you can pretend you are Richard Branson—with your own private "island" to impress your friends. Two of the three islands on the edge of the country's second-largest surf pool are large enough for 25 people; the third will accommodate 50. Where most water park pools offer a steady, predictable set of rather tame waves, Poseidon's Rage mimics the ocean by mixing things up. You might get a seven-footer, then a five-footer, then a nine-footer. Last year, the owners of Mt. Olympus bought The Bay of Dreams Indoor Water Park and Family Land Outdoor Water Park to create one of Wisconsin Dell's largest entertainment resort complexes, which includes indoor and outdoor (dry) theme parks. Mt. Olympus' Greco-Roman motif continues with a ride planned for a 2008 debut: The River Troy, touted as "the world's fastest river."

Leave it to imaginative minds inspired by Uncle Walt to turn a swimsuit-oriented attraction into a world of snow and ice. Based on a ski-resort theme, the 66-acre Blizzard Beach features a chair lift, slalom gates, ice cave and an eight-lane water slide that sends toboggan racers down snowy slopes. Summit Plummet is the world's tallest (120 feet) and fastest (55-60 mph) freefall waterslide, while Teamboat Springs is the world's longest whitewater raft ride (1,200 feet). Though the park is only four miles from Disney's Typhoon Lagoon, it is marketed as (wordplay alert) the "polar opposite" of its older sister.

Just before Christmas, Kalahari Resorts more than doubled the size of its water park in Sandusky, Ohio, to create the largest U.S. indoor water park under one roof at 173,000 square feet. The African-themed Kalahari keeps upping the game with new features, including a transparent roof, a wave pool with eight settings, the world's largest bowl ride, four-lane slalom racer slides and a spiral flume in which riders reach speeds up to 40 mph. There's also a basketball pool, kids safari, indoor/outdoor spa, swim-up bar, sun deck and private cabanas. Kalahari also operates a 125,000-square-foot indoor water park in Wisconsin Dells, scheduled for an expansion opening this coming December.

Schlitterbahn Galveston Island is the world's first convertible water park, capable of going from indoors to outdoors (and vice versa) in eight minutes. But its best innovation may be its Transportainment river system that allows guests to float ride-to-ride among three interconnected rivers. Among them is the Torrent River, a 1,250-foot-long, 20-foot-wide, tidal-wave river. Guests enter the river system from beaches scattered throughout the park or ride into it from the wave pool on the Aquaveyer, floating through sections of slow-moving water and whitewater rapids, detouring through two tube chutes and three uphill water coasters. The park grew by about 30 percent this year with a new area that includes seven attractions. Parking is free and you can bring in your own picnic basket.

The Noah's Ark 4D Dive-In Theater is not your ordinary water park attraction. In addition to 3-D visual effects, it features water drops, squirts and cannons, as well as "leg ticklers," vibration, scent, wind, "lightning" and bubbles. At 70 acres, Noah's Ark is billed as the largest outdoor water park in the United States. Attractions include 47 water slides, as well as the country's longest water coaster: the quarter-mile Black Anaconda. One of the newer rides is the Time Warp, a bowl ride that drops riders 70 feet at 30 mph.

Who needs the ocean when you can surf in the world's largest wave pool? At 395 feet by 115 feet, Typhoon Lagoon is one of the country's stand-out water attractions. The appropriately named Shark Reef is even stocked with nurse sharks, as well as tropical fish for your snorkeling pleasure. Perhaps because it caters to families with fewer thrill rides and more kid-friendly splashing attractions (not to mention the Disney affiliation), Typhoon Lagoon boasts the highest attendance of the world's many water parks, with 2.08 million visitors in 2007. If a shark encounter leaves you wanting to chill out, Disney's Blizzard Beach is just four miles away.

For those who get a thrill out of visiting film and television locations but who want to do more than have their picture taken in front of a café, rock formation or street sign, there's Raging Waters. The San Dimas water park appeared in the 1989 classic "Bill and Ted's Excellent Adventure," as well as Eddie Murphy's 2007 film "Norbit." And once you're over that thrill, you can ride the world's tallest headfirst toboggan waterslide, which sends riders through 600-foot flumes at speeds up to 35 mph. If that's too slow, the seven-story DropOut sends riders at near freefall, reaching 40 mph. If speed alone is not enough for adventurous sorts, the park offers rides through pitch-black tunnels: the 500-foot-long Dark Hole and 600-foot-long Neptune's Fury.

Since acquiring Wet 'n Wild in 1998, Universal Studios has upped the game in Orlando—competing with Disney's two nearby parks by adding to the attractions what it knows best: special effects. Last June, it launched Brain Wash, a six-story extreme tube ride with video footage. This June, it's relaunching The Black Hole with the addition of color explosions and sounds. Other attractions include The Bomb Bay, in which a trap door opens to send riders down a nearly vertical 76-foot chute, and the Wake Zone offering knee boarding, wake skating and towed tubing.

Rides at these 80,000-square-foot indoor and 120,000-square-foot outdoor water parks at Chula Vista Resort include the Flyan Mayan Zip Coaster (at nearly 40 mph and 850 feet, the world's fastest and longest indoor water coaster); the Jungle Adventure (a bowl ride that allows guests to select their own personal experience with sound and lighting effects, including disco); and Switchback Canyon, during which riders achieve zero gravity as they drop off a 50-foot freefall in an inflatable armchair. But who can overlook the luxury of lounging in a private cabana with a television, comfy furniture, soft towels, a ceiling fan and your own personal attendant to bring you another umbrella drink?