The Unterelbe or, in English usually the Lower Elbe, refers to the lower reaches of the river

Elbe The Elbe (; cs, Labe ; nds, Ilv or ''Elv''; Upper and dsb, Łobjo) is one of the major rivers of Central Europe. It rises in the Giant Mountains of the northern Czech Republic before traversing much of Bohemia (western half of the Czech Re ...

Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwee ...

influenced by the

tide Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon (and to a much lesser extent, the Sun) and are also caused by the Earth and Moon orbiting one another. Tide tables ...

s. It starts at kilometre 586, at the

sluice Sluice ( ) is a word for a channel controlled at its head by a movable gate which is called a sluice gate. A sluice gate is traditionally a wood or metal barrier sliding in grooves that are set in the sides of the waterway and can be considered ...

Geesthacht Geesthacht () is the largest city in the District of the Duchy of Lauenburg (Herzogtum Lauenburg) in Schleswig-Holstein in Northern Germany, south-east of Hamburg on the right bank of the River Elbe. History A church was built in what is today ...

, where the Elbe forms the border between

Lower Saxony Lower Saxony (german: Niedersachsen ; nds, Neddersassen; stq, Läichsaksen) is a German state (') in northwestern Germany. It is the second-largest state by land area, with , and fourth-largest in population (8 million in 2021) among the 16 ...

and

Schleswig-Holstein Schleswig-Holstein (; da, Slesvig-Holsten; nds, Sleswig-Holsteen; frr, Slaswik-Holstiinj) is the northernmost of the 16 states of Germany, comprising most of the historical duchy of Holstein and the southern part of the former Duchy of Sc ...

. It continues downstream, then forming the border between Lower Saxony and

Hamburg Hamburg (, ; nds, label=Hamburg German, Low Saxon, Hamborg ), officially the Free and Hanseatic City of Hamburg (german: Freie und Hansestadt Hamburg; nds, label=Low Saxon, Friee un Hansestadt Hamborg),. is the List of cities in Germany by popul ...

, before fully entering Hamburg territory. In Hamburg the Unterelbe forms two

anabranch An anabranch is a section of a river or stream that diverts from the main channel or stem of the watercourse and rejoins the main stem downstream. Local anabranches can be the result of small islands in the watercourse. In larger anabranches, ...

es,

Norderelbe The Norderelbe () (Northern Elbe) is one of the two big anabranches of the Unterelbe river in the area which is now the Port of Hamburg, Germany. The other anabranch is the Süderelbe. Together they form the island of Wilhelmsburg. See als ...

and

Süderelbe The Süderelbe () (Southern Elbe) is the biggest anabranch of the Unterelbe river in the area which is now the Port of Hamburg, Germany. Its natural flow path was redirected through the Köhlbrand. See also * List of bridges in Hamburg *List ...

, the latter now partially a cut-off meander. Where Norderelbe and Süderelbe used to reunite, at kilometre 634 there is a bay called the . This marks the beginning of the section of the Unterelbe which called the Niederelbe. After leaving Hamburg it forms the border between Lower Saxony and Schleswig-Holstein, again. The end it defined by the Kugelbake in

Cuxhaven Cuxhaven (; ) is an independent town and seat of the Cuxhaven district, in Lower Saxony, Germany. The town includes the northernmost point of Lower Saxony. It is situated on the shore of the North Sea at the mouth of the Elbe River. Cuxhaven ...

at kilometre 727.73. It continues further into the

Wadden Sea The Wadden Sea ( nl, Waddenzee ; german: Wattenmeer; nds, Wattensee or ; da, Vadehavet; fy, Waadsee, longname=yes; frr, di Heef) is an intertidal zone in the southeastern part of the North Sea. It lies between the coast of northwestern conti ...

as the Außenelbe, where it passes the Hamburg islands Scharhörn and Nigehörn.