The Douro, or Duero, crosses the southern half, running west-north-west; it also is unnavigable in its upper valley.
At the same time there are numerous, but unnavigable rivers.
From Vivi to Isangila, we must remember, the river is unnavigable.
Their violence makes them difficult to control, and they are unnavigable.
The scenery of the unnavigable portion of the river is full of singular and romantic424 beauty.
The rivers, known only at their mouths, seem to be unnavigable.
Mountain slopes comprise about two-fifths of the area of the country, and practically all of the rivers are rapid and unnavigable.
On account of the number of trunks of trees, it is unnavigable for large ships.
The Ya-lung is unnavigable, and the only craft on its green waters were three ferry boats, each about thirty feet long.
All are swift and unnavigable, save perhaps for a few miles from their mouths.