J. Galvin Giddings. University of Utah Press

Rockfall! Colossal pieces of rock and earth came tumbling down the unconsolidated wall behind us in the dark of night. The clattering rumble echoed back from a million stony facades that time and the river had cut out of Vilcabamba grandeur. It was an eerie effect in the dark of the canyon.

Chuck, sleeping closest to the cascade of rocks, ambled out on the beach, grumbling. "These cheap hotels don't hold up very well," he complained. He found a new pocket of sand, closer to the river, and we all dozed off again. But our sleep was broken at frequent intervals. All night, new pieces would break loose, and the repeated echoes would start again. The cliff was set back far enough from the river and from our camp to leave us unmolested, but in the wavering mirages and uncanny apparitions of half-sleep, the terrace seemed to tiptoe closer and unloose its arsenal of rock above our very heads. We awoke still on edge from the falling rocks, but our attention soon focused on the challenge ahead. Below us, the canyon turned gently right. Half a mile below, it broke sharply left on its final approach to the Chasm of Acobamba. We would catch no glimpse of the chasm until we reached that abrupt left bend.

But even getting to it might be difficult. The canyon deepened ahead, while the walls slowly converged, until at the chasm they practically came together. The unconsolidated terrace, which continued downriver from our camp, also converged slowly toward the river, broken only by scattered cliffs. The terrace loomed larger and larger in my mind as a hazard. For one thing, it shed its rocks like tears to splatter on all below. Worse, it was utterly unclimbable; we would not be able to escape directly over its crumbling face, no matter how severe our emergency. Far better were the vertical walls of solid rock nearby, which would at least stay firmly in place if we tried to climb them.

The heightened uncertainty of the canyon below, on its final approach to the Chasm of Acobamba, made reconnaissance advisable. Someone would have to go down to check it out. Jim and Chuck volunteered. They would have to go by kayak, because each shoreline was cut by impassable cliffs running out into the river. The plan was that the kayaks would be emptied of gear so they would be nimble and light for working back up through the current, past the rapids, and along the fading strands of shoreline. Jim and Chuck would have to have perfect judgment, or they could become trapped down there.

Going down a river is always easier than coming back up. The difficulty of every obstacle they encountered going downstream would be multiplied coming back. If they erred by thinking they could get past a cliff-bound section of river when they could not, the trap would slam shut above them, snaring them between giant walls and loose terraces to the sides and the Chasm of Acobamba below. They would then face the chasm, alone and unequipped, as the only way out of the canyon.

I shuddered at the risks as I watched them pick their way downstream, finally to disappear behind a cliff. I suddenly realized that in our haste we had not developed a contingency plan in case they should not return that day-or the next. Would it be best to seek help in effort to get them out; to rush into the trap after them; or to look for them from the thorny mountains above? I didn't know, and I prayed that a decision would never be necessary.

The canyon grew hot as we waited. The stillness of the day was broken only by the rippling current of the river, the buzzing of insects, and an occasional word exchanged between those of us remaining. I was buried in thought, trying to imagine what I would do, given various possible reports from those downstream. Uncertainty and confidence alternately took control of me. How can one judge risks objectively for such an uncommon venture? Where is the level path between foolhardiness and equally foolish fear? These were unanswerable questions, buried in the depths of subjectivity and emotion, but I turned them over and over in my mind. On the positive side, I told myself that I had explored and survived many other canyons and gorges before, although none quite so formidable as this. I could probabiv navigate what I could not portage or line. I could probably swim whatever I failed to navigate. Probably.

I thought of ending the worrisome monotony by hiking up through a break in the canyon wall and terrace on the left side of the river. It might be possible to find a route to the scarred mountain, around which the river turned in its giant left bend as it approached and then plunged through the unexplored chasm. Somewhere up there in the thorny foothills would be a few trails radiating from Hacienda Poyonco. If we had to go over the mountain, that would be the way.

With the lengthening absence of our comrades, I became convinced that I should start scouting the lower part of the route, in the eventuality that the gorge proved to be impassable. The longer their delay, the more likely it was that serious difficulties lay ahead in the chasm and that an alternative would be needed.

We cast our eyes downstream with increasing anxiety as the hours ticked by. I wished we could know how they were doing and what they saw down there. I had decided to begin my hike up the mountain, in part to reduce the tension of waiting, when two figures suddenly appeared on the left shore. We rushed down the shore and greeted them with an intensity more befitting friends lost a year at sea than those scouting half a mile of river. "What did you see?" we chorused. "Can you tell what's in the gorge?"

They told us that after disappearing from our sight, they had continued down the increasingly narrow canyon. They pulled over to a rocky shoreline on the left side, pulled their kayaks up among the rocks, and proceeded to work downriver along the broken embankment. After a quarter of a mile, their route was blocked by steep cliffs. They had two choices: they could scramble back to the boats, cross the river, then try the other side, or one of them could swim across the river from where they stood, where the cliffs had stopped them. After a moment of disagreement, they decided that Chuck would swim across the river, to save time. After swimming over to the right side, Chuck then worked down the rapid along the shore, swam 50 yards through a deep pool alongside a sheer cliff, climbed out on the right side at a break, then climbed up along the cliff for a better view. He was now at the great left bend, still half a mile from the gorge, and his view was still only fragmentary.