The walls ran close together and at the water were perfectly vertical for a hundred feet or so, then there was a terrace.

As we sailed down, the river was suddenly studded with pinnacles of rock, huge boulders or masses fallen from the heights.
By steering carefully we could pass among these and, keeping in the dividing line of the current, make for the head of a rocky island, on each side of which the waters plunged against the cliffs with great force as they dropped away to a lower level.

The danger lay in getting too far over either way, and it was somewhat difficult to dodge the pinnacles and steer for the island at the same time.

The Canonita went on the wrong side of one, and we held our breath, for it seemed as if she could not retrieve her position in the dividing current, but she did.

As we approached the head of the island our keel bumped several times on the rocks, while the current changed from the simple dividing line and ran everywhere.