It required some care to preserve their equilibrium, but then the water was not deep, and they knew, therefore, that there was no danger of being drowned if they should upset.
Things went on very prosperously, until, after a few minutes, the boys suddenly found themselves drifting into deeper water.

Their poles would scarcely touch the bottom.

Marco, who was not much accustomed to this kind of navigation, was at first somewhat alarmed, but the other boys told him to keep quiet, and they would soon drift into shallow water again.

They accordingly drew in their poles, and began to look over the edge of the boat into the water, to see if they could see any eels.

They saw no eels, but the water soon began to grow shallow again, and so the boys, feeling that they were in no danger, remained quietly in their places, looking idly into the water, talking about the various objects which they saw upon the bottom.
After some minutes spent in this manner, one of the boys looked down the stream, and saw that the boat was gradually approaching another of the rapids.
"Come, boys," said he, "we must go to work, or we shall be down over the rips." So the boys all took their poles and began to push the boat up the stream; but they found it harder than they had expected.