“Hey!” said Harlan, now animated. “I have an idea I want to test.” Apparently he was still looking at me, because he chuckled one more time before he walked over, grabbed the radios that were lying on a tarp, and brought them over to the giant ceramic water filter. He filtered a couple of gallons of river water and filled a big bucket. “This water is super clear now,” he pronounced as he submerged one of the radio sets and let it soak for several seconds.

Rob peered into the bucket and remarked, “That’s amazing,” and he described the clean filtered water turning to the color of café au lait. “The comm systems are waterproof,” Rob said, “but looks like silt and sand have been completely clogging the membranes and getting into the microphones, too.”

Rob high-fived Harlan and said, “Nice job, Harlan. You should be an engineer.”

After thoroughly soaking and drying all the other systems, the sound quality on the radios seemed to bounce back. They weren’t as good as new, but they were good enough to get me through. For extra protection, Skyler took little latex covers for injured fingers from the medical kit, covered the foam microphones, and sealed around the edges with tiny, tightly coiled rubber bands.

At breakfast, I chuckled when I heard Steven yelling, “Raker, where’s your rock?” I knew Rob must have been caught reaching for some sausage.

“I think it’s in my tent,” Rob stammered.

Steven sprinted ten feet across the sand and found a rock pile. He swiped one up and replied, “Well, here’s another one. Don’t lose it. Oh, and I’ll take that sausage patty there,” and he snatched it off Rob’s plate.

The next few days were spectacular as we dropped down into the deepest and oldest part of the canyon. As I ran my hands over the ancient schist, almost two billion years old, jutting straight up from the river, Harlan said, “Welcome to the basement of the Grand Canyon.” Some of the schist was smooth as marble through weathering and erosion; other sections were fluted and corrugated, and still others were scalloped and rippled from many millennia of being scoured by waves. We also entered Granite Narrows, the tightest section of the canyon at just seventy-five feet across. The walls here rose a mile above us.

Still in the narrows, we passed a feature called Helicopter Eddy. It was a super-turbulent, violently recirculating eddy formed by a cutout in the rock wall river left. Harlan said emphatically that we wanted to avoid it. It had a toilet bowl effect and could shove you up against the canyon wall and pin you there, and if you were able to dislodge yourself from the wall, the eddy fence was huge and roiling, making it extremely difficult to get back into the river.