The extreme purity of the black waters is confirmed by their transparency, and by the way they clearly reflect all the surrounding objects. The minutest fish are visible at a depth of 20 or 30 feet. It is easy to see the river bottom, which is not muddy but composed of a dazzlingly white granite or quartz sand. Nothing can be compared to the beauty of the Atabapo river banks, overloaded with vegetation, among which rise the palms with plumed leaves, reflected in the river water. The green of the reflected image seems as real as the object seen with your eyes.

We set sail on the 9th of March before dawn, nervous about the uncomfortable narrow boat in which we had to sleep on deck. The cabin (càmara de pozo) had no light or air and was merely a hold for provisions; we could only just fit our instruments in there. These inconveniences lasted only twenty days.