"Oh, this is great stuff," Jim Hungelmann said as he smiled ear to ear. "I love being in water ? hiking on these rocks. It's just wonderful."
Despite being the oldest, he is also the boldest, going up to jump three, four, even five times off the same cliffs. Some of them are 25 feet high or more.
"Maybe it's because I don't have that much time left, you know?" he said with a laugh.
Before the next toboggan run, the guides scout the river floor for sharp rocks, telling us to keep our elbows in, our feet up and our eyes open.
"It's a rush -- awesome!" Traub said as she disappeared into a torrent of white water and then plopped over an eight-foot waterfall into a deep pool below.
"Awesome!" said Kosmack, perhaps a little shocked that she'd made it this far.
As we jump, bump and slide down the river we're beginning to get a more complete picture of canyoning. You've heard the expression "up the creek without a paddle"? Well, canyoning is going to down the creek, as the paddle.
It's a safe bet that there is nothing at the theme parks back home quite like this.
Hungelmann follows the guides over one of the waterfalls headfirst.
"I just went backwards off that ledge there," he said, panting and pointing to the 10-foot drop he's just navigated. "It was awesome. ? It was just a free fall and then landing."
For the veteran canyoners among us -- the guides -- what we're doing is child's play. They fill us with awe and terror as they bound off cliffs 30 and 40 feet high, landing in pools of water that look only a little bigger than a teacup.
It looks daring and dangerous: If they don't jump way out, they'll crash into the cliff on their way down.
Alfonso Spoliansky, one of the guides, starts to say that canyoning isn't dangerous, but Manghera interrupts.
"Yes, of course, it's dangerous," he said, explaining the importance of checking the rapids and ponds for hazards after each rainfall. "It's not so dangerous when you follow the rules."
He confesses his company, Pachamagua, has had two accidents. One involved a tourist who hit his head even though he was wearing a helmet. The injury wasn't serious. The other involved a tourist who broke his leg when it got caught between two rocks.
But this extreme sport has seen much worse. In 1999, 21 young people were killed in a canyoning accident in Switzerland when flash floods inundated a narrow gorge after a rainfall. Two years later six managers were convicted of negligent manslaughter.
There is more risk here than in most sports and only fools fail to recognize that, but if fear runs through your veins, this is not the sport for you.
"You have to trust your guides," said Hungelmann. "These guides are good."
There is choice of jumps before the grand finale. Manghera offers a choice of a 25-foot jump, a smaller jump or a toboggan ride over a 15-foot waterfall.
"This is terrifying," said Traub as she stared at the toboggan ride. "I think this is a bit high for me. I'm not gonna lie, I'm a little nervous about this one."
She toboggans over the falls, no doubt concluding that the sheer force of the water won't give her time for second thoughts.
An airborne ride toward the end of the adventure introduces the uninitiated to "abseiling," a fancy word for "repelling," which is a fancy word for dropping like a stone while attached to a rope.
We all awkwardly strap climbing harnesses over our wet suits. Traub goes first. Secured to a rope, she goes headfirst over the cliff side. It is 100 feet down and just yards from the most ferocious and most spectacular waterfall of the day.
What a sensation. It is like peeking into a secret world as the water sprays in your face and lush vegetation stares you in the eye.
Then, there is one final, very high jump. Kosmack screams as she does it.
Incredibly, maybe miraculously, we all survived. We're all smiling.
And we all know what canyoning is about.