We entered down the tongue as Marieke yelled, “Right paddle … and stop! All paddle … charge!” and we encountered a terrific energy, like an earthquake. The boat pitched and bucked forward and back, left and right. It was dizzying as we rose up the front side of a colossal wave, everyone paddling like crazy. The blind kids in front were digging in hard, but the angle of the boat was so steep, the front half protruded into the sky, and they only dug at air. Then the boat crested the top, and lurched downward.

“Brace! Brace!” Marieke yelled from the back, and everyone hunkered down, lodging their feet even deeper under the rubber tubes. There was a terrific explosion as the bow hit the trough and stopped momentarily. The force was like a car crash, the stiff rubber boat folding and everyone being thrown forward, submerged in massive amounts of water and foam. It was a miracle that everyone stayed in the boat.

Riding out the tail waves and safe on the other side, we all cheered, raising our paddles in the air and trying to clap them together. A few of us missed, but after eight tries, we all made impact.

As we paddled through the flat sections, Marieke described to us the thick, silty color of the river, the clouds passing, and the canyon walls with their different colors—reds, browns, and blacks, like the layers of a birthday cake—each of the distinct layers representing different geological times throughout history. She said that in the inner gorge, the walls rose up more than a mile high in some places, and at the bottom of the canyon was some of the oldest rock on earth, almost two billion years old. She’d smack her paddle flat against the water so we could hear its rifle crack echoing to the top of the canyon walls. We even pulled the raft over so all of us could run our fingers across this smooth, hard sandstone worn down by the centuries.

She also described our entertaining safety guide, who also happened to be her little brother, Harlan Taney. He glided around us in a hard-shell kayak. His job was to paddle quickly to the action and assist any swimmers. She described him in his tiny kayak, constantly flipping upside down, staying under for what seemed like an impossible amount of time, and emerging upright from the dark water with a giant smile across his face. Crazy thing was that she said he was doing that on purpose—for fun. “I’ve never seen someone as comfortable in water as Harlan,” she said. “He’s been that way ever since I can remember. It’s like he’s half-human, half-dolphin.”