Oste (German pronunciation: [ˈoːstə, ˈɔstə]) is a river in northern Lower Saxony, Germany with a length of 156 km (97 mi).

The Oste flows through the districts of Harburg, Rotenburg, Stade and Cuxhaven and empties into the Elbe river near Otterndorf.

The Oste is part of the Deutsche Fährstraße, an institution similar to the American National Scenic Byways.

It connects various places between Bremervörde and Kiel with relation to the history of ferries and crossing of rivers, like the historic transporter bridges in Rendsburg and Osten.

The river has its source near Tostedt at the border of the Lüneburg Heath, flowing to the west passing Sittensen and Zeven, changing direction to north and passing Bremervörde, where influence of the tides is starting, Hemmoor and Neuhaus.