Neil and I were about to embark on the first raft descent of the upper Rio Bavispe in northern Mexico, a tributary of the Rio Yaqui north of the infamous Copper Canyon. As far as we knew, the river had been run only once, by a solo kayaker. This is my favorite type of multi-day expedition, a challenging trip with unbiased expectations, unanticipated situations and little beta. I had been exploring Mexican rivers for the past few years, devoting many trips to the waters just across the southern border in Sonora and Chihuahua. Our plan for Rio Bavispe was to run 103 kilometers from Mesa Tres Rios to Bacerac in five days, an easy pace. It turned out that we would have to hustle to make it to the take-out on time.