Inferno canyon | Earth River | Argentine | Los Angeles | Bermuda

It was rapids like Terminator and Inferno that prevented a raft descent of the river until 1991. An attempt to raft the Fu in 1985 almost ended tragically when one of the rafts was torn to pieces by the river. Hertz and Earth River made the first complete raft descent in 1991, and the first commercial descent the following year. Thanks to a new kind of raft, specially designed by Hertz, and endless scouting, both trips - and every Earth River descent since - were without incident. Hertz is obsessed with the safety of his customers, constantly drilling customers about what to expect and how to handle it. Hertz also uses safety rafts that stay with the boats in case any paddler is ejected.

We put in our first morning five miles from the Argentine border, just above Inferno canyon. The morning was warm, hot even, but the water was cold, so we donned wetsuits. For the next two hours, our 18-foot inflatable raft thundered down through a series of rapids - Inferno, Purgatorio, and Danza de los Angeles ("Dance of the Angels"). On our final rapid, a violent Class Five named Escala De Jacoba ("Jacob's Ladder"), our boat was sucked into a hole with such force that Eric, our guide, was thrown from the back of the boat. Amazingly, we all kept our heads, letting Eric's training regimen take over instead. We paddled the boat into an eddy and waited while Eric swam to shore. "It's 100 percent adventure, and yet it feels 100 percent safe," says Kim Carter, a businessman from Bermuda and one of my paddlemates, while we waited in the eddy for Eric to rejoin us.