▲Menominee River, northwestern Michigan. The waterway also snakes into northeastern Wisconsin. (Photo: Flickr/CC BY-SA 2.0)

▲Flipping out on the Zambezi River near Victoria Falls. (Photo: Flickr/CC BY-ND 2.0)

▲Roughing it on the Rangitata River, South Island. The river eventually enters the Pacific Ocean, northeast of Timaru. (Photo: Flickr/CC BY 2.0)

▲The Pacuare River flows approximately 108 km (67 mi) to the Caribbean. Along the way it can get pretty choppy. (Photo: Flickr/CC BY 2.0)

▲Thrills on the Shotover River in the Otago region near Queenstown on New Zealand's South Island. (Photo: Flickr/CC BY-ND 2.0)

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Bailing out on the Ocoee River, which flows northwestward through the southern Appalachian Mountains, Tennessee. (Photo: Flickr/CC BY-NC 2.0)

▲As extreme as it gets on the Middle Fork, American River, Northern California. (Photo: Flickr/CC BY 2.0)

▲Tipping the balance on the The Kaituna River in the Bay of Plenty region, North Island. (Photo: Flickr/CC BY-NC 2.0)

▲A wipeout on the Kawarau River, which drains Lake Wakatipu in northwestern Otagois, South Island. (Photo: Flickr/CC BY-ND 2.0)

▲About to turn turtle on the Sjoa River. The waterway provides the outlet from Lake Gjende at Gjendesheim in the Jotunheimen mountains of Jotunheim National Park. (Photo: Flickr/CC BY-NC 2.0)

▲Caught in a jam on the Rangitata River, South Island.The Māori name for Rangitata translates as "day of lowering clouds." (Photo: Flickr/CC BY 2.0)

▲OK. This one's for younger adventurers because the Phang nga River, near Phuket Island, is a favorite with novice rafters. Have fun! (Photo: Flickr/CC BY 2.0)

▲Approaching Klamath Wild and Scenic River southwest of Klamath Falls in south-central Oregon. (Photo: Flickr/CC BY 2.0)

▲Maneuvering into position on the Vuoksi River near Losevo, in the Leningrad region of the country.

▲Admiring the views on the Sagana (also called Thagana), it's the country's longest river.

▲Tackling the white water on the Chilko River in British Columbia.

▲Tackling the fierce Pillow Rapid on Gauley River, West Virginia.

▲Located in Idaho, the Salmon is also known as "The River of No Return" and is exactly where this raft is heading for.

▲The heart-stopping Strbacki Buk waterfall on the Una River in Una-Sana Canton.

▲The rain forests that surround the Pacuare River are home to exotic animal species, including the elusive jaguar.

▲Navigating the Selangor River as it meanders through lush jungle is tricky. The waterway eventually empties into the Straits of Malacca.

▲The view from the deck on the Thompson River in British Columbia, the largest tributary of the Fraser River.

▲About to disappear it seems under the Gariep River (Orange River) in Southern Africa, the longest river within the borders of Lesotho.

▲Surfing the Sesia River—a tributary of the Po—which flows through Piedmont in the country's northwestern region. It's one of Europe's most popular rivers for rafting and kayaking.

▲The boiling waters of the Zanskar River near the confluence of the Indus and Zanskar rivers in Leh district.

▲The Chattooga River in a bad mood. Approaching Bull Slice on this Georgia waterway will be familiar to movie buffs—'Deliverance' (1972) was filmed here.

▲Rafting the Sun Kosi River, known as the "River of Gold" and located not far from Kathmandu. It ends near the Indian border, in southeastern Nepal.

▲The 2,525-km (1,569-mi) Ganges rises in the western Himalayas to emerge at Rishikesh, where these people are about to be pulverized.

▲Taking the plunge on the Nile. This is the longest river in Africa (some say the world) and covers 11 countries including Uganda, where it leaves lake Victoria near Jinja—often considered its source.

▲The scenic Poudre River outside of Fort Collins, Colorado.

▲Only the bravest head for Godzilla rapids on the Upano River near Logroño.

▲A torrid North Johnston River, which passes through the Palmerstone National Park in tropical North Queensland.

▲The deceptive calm of the Yoshino River on the island of Shikoku. It's considered one of the three greatest rivers of Japan, along with the Tone and the Chikugo.

▲Meeting the Terminator rapids on Futaleufú River in northern Patagonia.

▲Going for it! The Sesia River, which is glacial in origin, flows through a number of pristine Alpine Valleys.

▲Traversing the shallows on Manavgat River, which originates on the eastern slopes of Western Taurus Mountains in southern Turkey.

▲Plunging down the famous Tutea Falls on the Kaituna River, near Rotorua on North Island.

▲Big-volume water on Karnali River, home to the notorious God's House rapid.

▲Meeting considerable resistance on the Vrbas River near Banja Luka, a tributary of the Sava River.

▲This is what a wall of water looks like on the Ottawa River, which spans the provinces of Ontario and Quebec.

▲Rocking and rolling on the Salmon River, as it flows for 685 km (425 mi) through central Idaho.

▲A swollen Paiva River flows through the Arouca Geopark in the north of the country.

▲The power and the glory! The thundering Ganges is one of the most fearsome rivers in the world.

▲About to hit a wall of white water on the Koksu River near Taldykurgan.

▲Powering along the Clear Creek River just outside of Denver.

▲The Southern Bug, or Southern Buh, in Mygiya flows southeasterly into the Bug Estuary (Black Sea basin).

▲There's no room for error on the Kuranda River in Queensland.

▲Well below the waterline on the Pastaza River in Sangay National Park.

▲Taking on the Big Eddy rapids at the Bend on Deschutes River, Colorado.

▲The Pastaza River offers watersports enthusiasts a South American white water adventure.

▲No going back! Hitting the rapids on the Maetang River in Chiang Mai.

▲The Tara, which flows through Montenegro and Bosnia and Herzegovina, is another European river favored by extreme sports enthusiasts.

▲Making a determined splash on the Kiulu River in Sabah, Malaysian Borneo.

▲Getting ready for the drop on Chulishman River in the country's Altai Republic region.

▲Stretching out on the Soca River in Triglav National Park.

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The worst is behind these rafters as they clear the rapids on Shotover River in Queenstown, South Island.

▲A lull in the rapids on the Manavgat in Green Canyon. The Manavgat River is one of the most popular destinations among rafters in Turkey.

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As extreme sports go, white water rafting is up there with the most challenging. Jumping into an inflatable raft to navigate a menacing river of thunderous waves, swirling eddies, pummeling holes, and the odd massive boulder or two is not for the fainthearted. In fact, it helps if you're one oar short of a rowboat. But if fear is your friend and you spit in the face of adversity, then this insane watersport is for you. PS: beginner swimmers need not apply!

Browse the gallery for a dramatic paddle downstream on some of the wildest rivers on the planet.