Tropical Islands Resort, Germany

Visitors swim in the lagoon at the Tropical Islands Resort, Feb. 15, 2013, in Krausnick, Brandenburg, Germany. (Sean Gallup/Getty Images)

In the middle of a searing summer, indoor water parks can serve as oases to those looking for a refreshing, water-filled getaway. At these amazing indoor water parks around the world, guests can splash, surf, slide and spa all-year round, and enjoy everything from wave pools and super loops to tipping buckets and thermal baths.

Opened in 2004, the Tropical Islands Resort in Krausnick, Germanyoccupies a former Soviet military airship hangar. Guests at the resort are treated to a tropical holiday experience, complete with a beach, lagoons, waterfalls, exotic flowering gardens, restaurants, water slides, evening shows, saunas, an adventure park and overnight arrangements ranging from tents on the beach to luxury accommodations.The interior is kept at a temperature of 79 degrees round-the-clock, 365 days a year, and the eight football fields of landscaping is made barefoot-friendly by an under-floor heating system, according to the Washington Post.The resort is considered to be the biggest free-standing hall in the world, measuring at 1,181 feet long, 689 feet wide and 351 feet high. It is so big; it could house the Statue of Liberty.

NEXT: Olympic stadium transformed into water park

Happy Magic Water Cube, China

Once the venue of the Olympic swimming competitions, where Michael Phelps broke records and won eight gold medals, China's National Aquatic Center or "Water Cube" in Beijing is now home to "Happy Magic Water Cube Water Park," with numerous water-rides, spa pools, wave pools, a lazy river and 13 water slides including the Bullet Bowl and Speed Slide, according to the Daily Mail.

The tallest tower in the park is a ride called the "Tornado," an enclosed water slide shaped like a four-leaf clover that features a 90-degree turn before heading into a quicker 180-degree and a thrilling loop in a funnel before dropping to the pool below, the official website explains. The temperature-controlled water park, which features an underwater theme (complete with floating giant jellyfish) and opened in August 2010, took nearly a year to complete and cost around RMB 350 million (about $51 million), according to CNN.

NEXT: Boogie board all-year round in Ohio

Kalahari Resorts Waterpark, Sandusky, Ohio

Kalahari Resorts' Waterpark in Sandusky, Ohio features a 12,000-square-foot Wave Pool, water coasters, tube slide, indoor spa, swim-up bar, and even a basketball pool. (Kalahari Resorts)

Want to Boogie board in the winter? Kalahari Resorts' waterpark in Sandusky, Ohio makes it possible with its "Flowrider," where 50,000 gallons of water each minute flow to create a 5-foot ocean-like wave.

Guestscan also catch some rays under the Texlon transparent roof and enjoy the 12,000 sq. ft. wave pool. The park also features Swahili Swirl 60' diameter bowl raft ride, Zip Coaster uphill water rollercoaster waterslide, Cheetah Race 4 lane mat slides, Rippling Rhino and Victoria Falls raft rides, lazy river, and an indoor spa.

NEXT: A giant water park in Niagara Falls

FallsviewIndoor Waterpark, Canada

The Fallsview Indoor Waterpark in Niagara Falls features 125,000 square feet of 6-story high water slides, wave pool, plunge pool and a 1,000-gallon tipping bucket.

But Fallsviews doesn't just cater to splash-happy kids. Adults can soothe their tired muscles in the Horseshoe Hot Springs, where jets swirl warm water in one of two oversized adults-only whirlpool tubs.

NEXT: Four indoor water parks in one resort

Wilderness Resort, Wisconsin Dells, Wis.

View of the WaterDome at Wilderness Resort in Wisconsin Dells. The dome has a see through roof that people can tan under indoors year-round and is home to the country’s largest indoor wave pool. (Wilderness Resort)

Consisting of more than 600 acres, the Wilderness Resort located in Wisconsin Dells is home to three resorts — Wilderness Hotel and Golf Resort, Wilderness on the Lake and Glacier Canyon Lodge — and four indoor waterparks.

One of the biggest indoor parks in the resort is the Wild WaterDome, a 70,000 square footwater park with a see-through roof that actually allows guests to tan indoor year-round. It is also home to the America’s largest indoor wave pool, the Great Wave.

NEXT: Home to the largest indoor wave pool

World Waterpark, Canada

Located in the West Edmonton Mall in Edmonton, Alberta, Canada, World Waterpark boasts the world's largest indoor wave pool, which features five wave panels with 1,500 horsepower (1,100 kW) generating waves (in 5 to 10 minute sessions) of approximately 5–6 feet.

And budding Canadian surfers can get their start at the World Waterpark. Surf lessons are available for guests ages 10 and up and a surf club caters to those who want to improve their surfing skills and fitness and surf year-round.

NEXT: Europe's largest thermal bath complex

Therme Erding, Germany

Perhaps the world's most relaxing "water park,"Therme Erding in Bavaria, Germany is Europe's largest thermal bath complex. The complex is not only home to 20 kid-friendlywaterslides, but it also houses thermal baths (water is maintained at 93 degrees Fahrenheit), pool bar, saunas, steam rooms and lounges.

The thermal baths also offer "sauna paradise" during the summer, when the venue opens their three roofs so guests can enjoy the sun and stars while bathing in the exotic water world.

NEXT: A Swiss-Austrian village- themed water park

Avalanche Bay, Boyne Hills, Mich.

Themed as a Swiss-Austrian village hit by an avalanche, Avalanche Bay waterpark in Boyne Hills, Mich, transports guests to a winter wonderland enjoyed at 84 degrees. The 88,000 square foot waterpark features 12 aquatic adventures including an extreme body slide, kids pools, surf simulator, and 100+ game arcade. (Photo courtesy of Boyne Mountain Resort)

A Swiss-Austrian village in Michigan? Avalanche Bay Indoor Water Park at Boyne Mountain Resort recreates a quaint European town with water slides, wave pools, lazy river, hot tubs and a raging wall of water from "Splasherhorn Mountain." And guests enjoy the wild, splashy activities in a maintained temperature of 84 degrees all-year round.

In December 2013, Avalanche Bay unveiled its newest attraction,The Big Couloir, a ProSlide SuperLoops. The ride starts off withguests entering a launch capsule with a trap door on the bottom. The floor suddenly drops out and guests are propelled into the narrow enclosed tunnel and instantly accelerated to a top speed of 38 feet per second. G-Forces glue the rider to the wall the entire way around the tight 360 degrees SuperLoops before the watery run out brings them to a stop at the bottom.

NEXT: Europe's largest indoor water park

Alpamare Waterpark, Switzerland

Alpamare in Switzerland is Europe's largest indoor water park. It features a surf wave indoor pool, the Rio Mare River open-air swimming pool, the Alpa Thermal Bath with whirlpools and the 36-degree Celsius Iodine-Saline Thermal Bath. (Alpamare)

Located inPfaeffikon, Switzerland, Alpamare is Europe's largest indoor water park, and home to the continent's longest water slides.The complex also features a surf wave indoor pool, the Rio Mare River open-air swimming pool, the Alpa Thermal Bath with whirlpools and the 36-degree Celsius Iodine-Saline Thermal Bath. Sauna fans will further attractions such as a Bio-Sauna, a Finnish Sauna and an Adventure Sauna with special infusions, or the steam bath with light effects.

NEXT: An indoor beach in Japan

Ocean Dome, Japan

The Seagaia Ocean Dome in Japan was for years, one of Kyushu Island's most popular attractions. An artificial, heated, indoor beach, Ocean Dome featured a fake flame-spitting volcano, artificial sand, artificial palm trees and the world's largest retractable roof, which provided a permanently blue sky even on a rainy day, according to Amusing Planet. The air temperature was always held at around 30 degrees Celsius and the water at around 28.

Unfortunately, the Ocean Dome was officially closed on October 1, 2007 as part of a renovation and partial re-branding of the resort that owns the venue. But visitors to Kyushu Island looking for some water fun don't have to fret. An actual beach is locate donly 300 meters away from the site of the Dome.

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