All are swift and unnavigable, save perhaps for a.
It is lowest in November, and rocks, shallows, and the remains of old dams then render it almost unnavigable.
Pascagoula and Point aux Chenes bays; separated from it by the shallow and practically unnavigable Mississippi Sound is a chain of low, long and narrow sand islands, the largest of which are Petit Bois, Horn, Ship and Cat.
From Shigatse, which stands near the mouth of the Nyang Chu, to the Kyi-chu, or Lhasa river, there is no direct route, the river being unnavigable below Shigatse.
Swollen by the melting of the winter snows and by heavy rains in the mountains, it is frequently a torrent, and is thus, except in the last few miles, unnavigable for either boats or rafts.