Its mouth is divided by sandbanks into many channels.
Both are navigable, though comparatively shallow and filled with sandbanks.
Above Agram the Save is used chiefly for floating rafts of timber; east of Sissek it is navigable by small steamboats, but, despite its great volume, the multitude of its perpetually shifting sandbanks interferes greatly with traffic. Steamers also ply on the Una, the Drave below Barcs, and the Danube.
Off the west coast, which is very irregular, lie the islands of Riigen, Usedom and Wollin; the coast of Farther Pomerania is smooth in outline and is bordered with dunes, or sandbanks.
(where rapids interrupt the currents) the valleys open out and the rivers wind in tortuous channels often choked by sandbanks.