The Havel () is a river in northeastern Germany, flowing through the states of Mecklenburg-Vorpommern, Brandenburg, Berlin and Saxony-Anhalt. The Havel is a right tributary of the Elbe. However, the direct distance from its source to its mouth is only . For much of its length, the Havel is navigable; it provides an important link in the waterway connections between the east and west of Germany, as well as beyond.
Source
The source of the Havel is located in the Mecklenburg Lake District, between Lake Müritz and the city of Neubrandenburg. There is no obvious visible source in the form of a spring, but the river originates in the lakes in the Diekenbruch near Ankershagen, close to and south-east of the watershed between the North and Baltic seas. From there the river initially flows southward, eventually joining the Elbe, which in turn flows into the North Sea. Every river north-east of it flows to the Baltic Sea. The river enters Brandenburg near the town of Fürstenberg. In its upper course and between Berlin and Brandenburg an der Havel the river forms several lakes.
The Havel's main tributary is the Spree, which joins the Havel in Spandau, a western borough of Berlin, and is longer and delivers more water than the Havel itself above the confluence. The second largest tributary is the Rhin, named in the Middle Ages by settlers from the lower Rhine. At the southern end of the Ruppiner See, weirs can distribute the waters of the Rhin either east- or westwards, rejoining the Havel in two places apart along a straight line, and more than apart along the course of the river.
The region around and north of the middle Havel is called the Havelland. It consists of sandy heights, sometimes called Ländchen, and low marshes, called luchs. A few kilometres of the river before its confluence with the Elbe near Havelberg are in the State of Saxony-Anhalt. Due to its minimal gradient it is susceptible to high waters in the Elbe.
Unless in extreme floods, if the dike of the Elbe is submerged, the discharge of the Havel is improved by the Gnevsdorfer Vorfluter (something like "Gnevsdorfer outfall"). By this canal, the mouth of the Havel, that naturally would be near Havelberg, is placed downstream. As the course of the Elbe has a higher gradient than the Havel, the water level of the Havel in Havelberg can be kept below the Elbe (at the junction of the traverse communicating canal, protected by a lock).
Towns along the river include: Fürstenberg, Zehdenick, Oranienburg, Berlin, Potsdam, Werder, Ketzin, Brandenburg, Premnitz, Rathenow and Havelberg.
History
In earlier Greek or Latin sources, such as Tacitus's Germania, the name of the river was also written as Habola, Habula, Havela. The river name Havel is related to German Haff, habe, hafen, MHG Hafen meaning port, harbor).
The Slavic people who later moved into the Havel area were referred to in German sources as Heveller (occasionally as Havolane).
<!--Among others, there are four important bridges, in Spandau, in Potsdam, in Brandenburg and in a western suburb of that town; and Berlin has a large number of bridges.-->
Navigation
thumb|left|The Havel in [[Blankenförde is navigable to canoes and light craft only]]
The Havel is navigable from the Mecklenburg Lake District to its confluence with the Elbe. Whilst its upper reaches carry little other than leisure traffic, further downstream it provides an important link in the German commercial waterway network, carrying traffic from the Rhine and the North Sea to Berlin and Poland.
From a navigation perspective, the Havel can be split into four sections with somewhat different characteristics and different administrative arrangements.
Head of navigation to Liebenwalde
thumb|left|The Havel passing through Schwedtsee
thumb|left|Foot and lift bridge in Zehdenick
The Havel is navigable to canoes and similar small craft from close to its source. Motor craft are prohibited above the first lock at , which links the Useriner See to the Großer Labussee. The stretch of the river between this lock and the junction with the Oder–Havel Canal is administered as part of the Obere–Havel–Wasserstraße, along with various connecting canals and waterways.
From Zwenzow downstream to Liebenwalde is a distance of . In this distance the navigation passes through the lakes of Großer Labussee, Woblitzsee, Wangnitzsee, Großer Priepertsee, Ellbogensee, Ziernsee, Röblinsee, Baalensee, Schwedtsee and Stolpsee. It also descends through the locks at Wesenberg, Steinhavelmühle, Fürstenberg, Bredereiche, Regow, Zaaren, Schorfheide, Zehdenick, Bischofswerder and Liebenwalde.
At Hennigsdorf, downstream of Liebenwalde, the Havel Canal joins the river on the west bank. This canal connects to Paretz, on the Havel downstream, and was built in the 1950s to allow East German vessels to avoid the stretch of the river under the political control of West Berlin. Some further downstream, the Berlin-Spandau Ship Canal joins the river on the east bank, providing a connection to central Berlin without passing through the lock at Spandau.