There comes a moment when you're stuck in a canyon, with rock walls soaring on either side, that you realize there is no way out but down.
That's where I found myself when I went canyoneering deep into the mountain crevices of an Arizona chasm known as Bear Canyon with Rich Rudow and Todd Martin. They are part of a new generation of modern explorers who risk death for the privilege of being the first humans to see the last of the American unknown.
Rudow and Martin are like the Lewis and Clark of canyoneering, seeing places no human eyes have graced before.
Bear Canyon, a few hours north of Phoenix, is a bunny slope when compared with Rudow and Martin's regular exploits, but it still is home to the natural beauty that draws these rugged canyoneers to explore them. These guys scale skyscraper-high cliffs, navigate slippery rappels and face the nagging realization that rescue is nearly impossible from previously uncharted slot canyons. Not cell phones, not even satellite phones, nor GPS will not work in these mountain fissures, so Rudow said their climbing gear means everything between life and death.
"Search-and-rescue guys can't even get to you fast," Rudow said. "If they knew where you were in the first place. You kind of push the edge and every once in a while you get into a pickle and every time you get into a pickle, you learn something new and try not to make that mistake again."
Canyoneering is a sport that includes rappelling, caving and climbing in which the climber knowingly maroons himself in the bowels of vertiginous slot canyons -- think the movie "127 Hours" and Aron Rolston cutting off his own arm. Rudow and Martin were part of the team behind the documentary titled "The Last of the Great Unknown" about exploring the hundreds of canyon tributaries that originate in the Grand Canyon.
Over the past few decades, canyoneering has emerged from the domain of a tiny subculture to nearly mainstream. There are now guidebooks, companies dedicated to outfitting these modern explorers and guided canyoneering tours at national parks. But few possess the fortitude of Martin and Rudow who go where cell phones don't reach and maps haven't been charted.
"Nightline" producer Ben Newman and I camped out with the canyoneering duo, getting up at the crack of dawn to gear up and begin the march to our climbing spot. We had no maps, no GPS, no satellites and no way to communicate with the outside world.
"We're leaving civilization, as much as it is, behind at this point," Rudow said.
He and Martin took us to what they called one of their favorite "bunny hills." Even though we're in the arid Arizona landscape, we donned wetsuits so we could stand the gauntlet of frigid water below us in the canyon. As we moved deeper into a narrower part of the mountain, the geography began to change around us as the light reflected off the walls. It was about a 15- to 20-foot drop below us.
We eventually reached a "pothole," a naturally forming pool of teeth-chattering water inside the canyon that can reach depths of 30 feet deep, according to Rudow.
"One of the important rules of thumb is you never commit the entire party to a pool like this or everyone gets trapped," Rudow said. "Send your most dispensable person first and see if they can flail their way out the other side."
Our senses are assaulted by the cold water and the cathedral-like canyon walls, but the view of the light falling on the mountain crevices was stunning.
"I look at a place like this and I always have a sense of exhilaration," Rudow said. "We may be the first ones to ever see it."
But later into the climb, thunder starts rolling in and with it comes the threat of getting trapped by a flash flood -- one of the many dangers of exploring canyons. If that happened, we would be in bad shape.
"No way out of that," Rudow said.