For military purposes the republic is divided into five districts, the northern desert provinces forming the first, the central provinces as far south as the Bio-Bio the second and third, and the southern provinces and territory the fourth and fifth.
This maritime range is traversed by several river valleys, some of which, like the Bio-Bio, are broad and have so gentle a slope as to be navigable.
The largest is the Bio-Bio, which has a total length of 220 m., 100 of which are navigable.
BIO-BIO, an inland province of southern Chile, bounded N., W.
By Arauco, Malleco and Bio-Bio, E.
Through Bio-Bio and Cautin.
Bio-Bio, Chile >>
During the years which have elapsed since the War of Independence the territory south of the Bio-Bio has been effectively occupied and divided into six provinces, Chiloe and the neighbouring islands and mainland to the east became a province, and four provinces in the northern deserts were acquired from Bolivia and Peru.
In central Chile above the Bio-Bio river the lakes are small and have no special geographical interest, with the exception perhaps of the Laguna del Maule, in 36° 7' S., and Laguna de la Laja, in 37° 20', which lie in the Andes near the Argentine frontier and are sources of the two rivers of the same names.
Below the Bio-Bio river there is a line of large picturesque lakes extending from the province of Cautin, south through that of Llanquihue, corresponding in character and position to the dry lacustrine depressions extending northward in the same valley.