Fortunately we're in safe hands. As the owner of Middle Fork River Tours, Clint is one of 26 commercial operators with a licence to run the Middle Fork. Between them, he and his team of seven guides have navigated the river more than 600 times.
While he steers us expertly through a maze of exposed rocks, I lie back and admire the scenery. All around snow-capped mountains rush down to the river, their sides studded with Douglas firs and lodgepole pines. Above us swifts swoop for insects while clouds of butterflies flicker across the bow.
Clint runs both oar boats and paddle boats on the Middle Fork, which means you can choose to be ferried in comfort while someone else does all the hard work or get active yourself and paddle. For the ultimate adrenaline rush you can even take on the rapids in a 2m-long inflatable canoe known as a ducky.
At midday we stop for lunch at a shaded grove on the riverbank. Ten minutes later, a spectacular buffet of pita bread, cold meats, dips and salads miraculously appears. For dessert, there are peach slices and homemade chocolate chip cookies from Clint's wife Molly.
It's the first in a succession of unexpectedly good meals that are magically conjured up from the depths of the rafts. Our dinners over the next few days will include handmade crab cakes and steak bearnaise; breakfasts will range from eggs benedict to French toast with maple syrup.
One of the big advantages of this trip over other multi-day rafting packages is that the Middle Fork's steep gradient allows a sweep boat laden with supplies to be sent ahead each day. It means that when we pull into camp each afternoon, our tents are already set up. All we have to do is change out of our wetsuits, put on some dry clothes and take a seat around the campfire.
Half an hour later the bar is open and I'm enjoying a gin and tonic and an hors d'oeuvre of cured pork with teriyaki sauce in the middle of the largest forested wilderness area in the lower 48 States.
Meals such as steak bearnaise and crab cakes are conjured up on an open fire on the banks of the Middle Fork.
After dinner, people gather around the campfire to swap stories over a glass of wine. Someone has brought a ukulele so one night we have a sing-along. Another evening, Clint organises a fiercely contested game of Pass the Pigs. By midnight everyone is in bed. Most guests retire to their tents and most of the guides sleep outside on mats.
Our group of 23 is a varied bunch. They include a father and daughter from Boston, a family of four from Seattle, three wisecracking friends from Philadelphia and another extended family from Idaho. The youngest is 14; the oldest is 78.
The number of families is a revelation. It's refreshing to see teenage boys fishing rather than glued to an Xbox, and college girls singing songs around the campfire rather than plugged into their iPods.
As we lose altitude, the dramatic high-alpine landscape mellows into rounded sage brush-covered hills before the river narrows and we plunge into North America's second-deepest canyon. For the last 40km of the trip, we're dwarfed by Impassable Canyon's towering granite walls. The riverside path disappears; the only way out is to follow the river.
During this time we hit some of the biggest rapids of the trip: stomach-flipping drops and frantic wave trains through a pinball maze of lethal-looking rocks. Each one is celebrated with shrieks of excitement and a high-five of paddles.
When we finally exit the Middle Fork and hit the confluence with the main Salmon River, everyone is notably subdued. We're just a few kilometres from the take-out point - not far from hot showers, proper toilets and clean clothes.
Yet all I want to do is go back and do it all again.
CHECKLIST
Getting there: Qantas flies daily to Los Angeles via Sydney. Internal flights from Los Angeles to Boise, Idaho take about two hours. The trip starts at Stanley, Idaho, a three-hour drive from Boise.
Where to stay: Before and after the trip, most guests spend the night at Mountain Village Resort in Stanley.
On the river: Middle Fork River Tours runs four-, five- and six-day trips from June to September. Trips include all meals, drinks and transport to and from Stanley. For all scheduled departures see idahosmiddlefork.com.
Further information: See DiscoverAmerica.com and visitidaho.org for more on visiting Idaho.
The writer was a guest of Middle Fork River Tours and Idaho Tourism.
