If you're keen to beat the sweltering summer temperatures and embrace adventure you might consider cooling off with a whitewater rafting trip. Online travel adviser Cheapflights offers its top 10 whitewater rafting destinations to experience the thrills and chills of this splashy adventure sport. Reuters has not endorsed this list:
1. Grand Canyon National Park, United States
Sign up for a single- or multi-day excursion on rivers that wind through America's most astounding natural wonder - the Grand Canyon. Spend hours, days - even weeks - on a professionally guided tour of waterways that range from placid to downright wild. Start at Glen Canyon Dam at the northeast part of the gorge and, from there, let your tour director - or your own paddle, should you choose - be your guide.
2. Ottawa River, Canada
The Ottawa River does a lot more than distinguish the border between Quebec and Ontario. The behemoth waterway is also Canada's most popular destination for rafting and kayaking. Luke-warm waters attract families and die-hard rafters each summer to steer through a valley thought to be more than 175 million years old. Take the kids for a leisurely paddle, or put on helmets with more competitive friends and race down the wondrous archipelago at top speed.
3. Glacier National Park, United States
Travelers aiming to combine whitewater rafting with other outdoor excursions need look no further than Flathead River in Montana's Glacier National Park. More than a million acres of preserved ecosystem and 700 milesof walkable trails make this nature lover's paradise an ideal spot for hiking and, of course, rafting. Pilot your inflatable vessel along the 158 miles of pure, unadulterated water, sourced directly from the Rocky Mountains.
4. Magpie River, Canada
It'll take you eight days to steer the escalating rapids of Quebec's Magpie River. Pitch a tent along this scenic stretch of river and savor its splendor, including the northern lights, in between day-long floats. Grade V rapids - the toughest classification recommended to raft - will greet you at the end of your week-long journey at Magpie Falls, a 125-foot vision of cascading water.
5. Pacuare River, Costa Rica
Also known as the Rio Pacuare, Costa Rica's Pacuare River is a delightful escape with varying degrees of difficulty that last approximately 67 miles. Divided into the Upper Upper, Upper, and Lower sections, the river's range of difficulty spans from Grade II to V - perfect for novice and veteran rafters alike. Surrounded completely by acres of lush rainforests, sailing down the Pacuare toward the Caribbean may mean introducing yourself to Costa Rica's wildlife, like monkeys, exotic birds and jaguars.
6. Futaleufu River, Chile
Arguably the best river in the world for experienced rafters to tackle, Chile's Futaleufu River offers both spectacular views and intense rapids. The stream, which cascades from lakes in the Los Alerces National Park and the Andes Mountains, is renowned for its deep-blue waters and Grade V drops. Recommended for skilled rafters with years of experience, the Futaleufu serves up long stretches of excitement at a time like the Wild Mile, a series of rapids that'll keep any athlete on his or her toes - scratch that - seat.
7. Apurimac River, Peru
Earning bragging rights for rafting part of the world's largest river is reason enough to fly to southern Peru for a rafting trip this year. The Apurimac River sources the Amazon, providing kayakers and whitewater rafters a chance to see South America's magnificent wilderness up close. Grade IV rapids - and a four-day commitment - attract skilled rafters with an appreciation for camping and the great outdoors.
8. Zambezi River, Zimbabwe and Zambia
Only expert rafters should attempt to tackle the intense swells and challenging rapids that the Zambezi River is so wildly famous for. Separated into the upper and middle Zambezi by Victoria Falls, one of the Seven Natural Wonders of the World, the river is nearly 1,600 miles of nature at its finest. Look for hippopotamuses and crocodiles along calmer stretches of the river, and brace yourself for massive drops and death-defying rapids along the no-nonsense parts, including the Batoka Gorge.
9. White Nile, Uganda
Maneuvering a boat full of rafters along the Bujagali Falls near the mouth of Lake Victoria is an adventure you'll never forget. The White Nile, a tributary of the actual Nile River, flows through Sudan, Rwanda, Tanzania and Uganda. Inexpensive rafting companies have set up shop near the most exciting part of the river in Uganda, combining world-class rafting with an introduction to Africa's astonishing landscape. Grade V rapids ease into harmonious currents, promising rafters both relaxation and thrills in a single afternoon.
10. North Johnstone River, Australia
The four- or six-day expedition along the North Johnstone River in North Queensland's World Heritage rainforests is considered one of the best travel adventures in the world. Ride a helicopter to the beginning of your unforgettable journey and wind your way through Grade V rapids and truly amazing scenery. Not for the faint of heart, North Johnstone offers days on end of the most demanding - and rewarding - whitewater rafting out there.