Among these the Apure, Arauca, Meta and Guaviare hold the first rank.
The Apure is formed by two great rivers, the Uribante and Sarare.
From the Uribante-Sarare junction to the Orinoco the length of the Apure is 645 m., of which Codazzi makes the doubtful claim that 564 are navigable, for there are some troublesome rapids 114 m.
Above its mouth, where the Apure is 3 m.
A few large streams enter the lower Apure from the south, but they are frequently entangled in lateral canals, due to the slight elevation of the plains above sea-level, the waters of the Apure, especially during flood time, having opened a great number of canos before reaching the Orinoco.