Happily, it was under these latter conditions that the jangada was to proceed; but, cumbrous in its movements, it could not keep up to the speed of the current which ran past it. There are also to be taken into account the stoppages occasioned by the bends in the river, the numerous islands which had to be rounded, the shoals which had to be avoided, and the hours of halting, which were necessarily lost when the night was too dark to advance securely, so that we cannot allow more than twenty-five kilometers for each twenty-four hours.

In addition, the surface of the water is far from being completely clear. Trees still green, vegetable remains, islets of plants constantly torn from the banks, formed quite a flotilla of fragments carried on by the currents, and were so many obstacles to speedy navigation.

The mouth of the Nanay was soon passed, and lost to sight behind a point on the left bank, which, with its carpet of russet grasses tinted by the sun, formed a ruddy relief to the green forests on the horizon.