The Oder (Odra in Polish and Czech) is a Central European river about 840 km long that rises at 634 m on the slopes of Fidlův kopec in the Oder Mountains of the Czech Republic, flows north through Ostrava and western Poland past Wrocław and Szczecin, and reaches the Baltic Sea through the Szczecin Lagoon. For 187 km it forms the border between Poland and Germany as part of the Oder–Neisse line, fixed after the Second World War. Its basin covers 119,074 km², 89% of it in Poland, and together with its tributaries it delivers about 17 km³ of water a year, roughly 540 m³/s, into the Szczecin Lagoon. It matters as a shipping route from industrial Silesia to the Baltic, as Poland’s second-longest river by total length, and as a political boundary that took 45 years to settle, from the Potsdam Conference of 1945 to a treaty in 1990. The best way to know it is to travel it, from a spring in a military training area to three mouths between the islands of Usedom and Wolin.
Fidlův Kopec and the Libavá Training Area: The First 112 km in Czechia
The Oder begins in the Oderské vrchy (Oder Mountains), a low range of the Nízký Jeseník in the Eastern Sudetes whose highest point, Fidlův kopec, reaches 680 m. The spring itself lies at about 634 m, in a saddle below the summit near the village of Kozlov in the Olomouc Region, inside the Libavá military training area. The army zone keeps the hills almost empty of people; apart from the trails to the source of the river, the area is closed to visitors. The nearest towns are Olomouc to the west and Lipník nad Bečvou and Hranice to the south, and the little town of Odry, downstream to the northeast, takes its name from the river.
From the source the young river heads northeast past the Moravian Gate, the low pass that separates the Sudetes from the Western Carpathians. About 112 km of the Oder lie in the Czech Republic, and 7,246 km² of its basin, roughly 6%, drains Czech land.
Ostrava, Bohumín and the Olza: The Oder Becomes a Border
The first city on the Oder is Ostrava, the Czech Republic’s third-largest, with about 281,000 inhabitants and a wider conurbation of around 500,000. It stands at the meeting of four rivers, the Oder, the Opava, the Ostravice and the Lučina, and grew on a major coalfield into the “steel heart” of Czechoslovakia. The Ostravice still divides the city into Moravian Ostrava and Silesian Ostrava, a reminder that the river valley here straddles two historic lands.
Below Ostrava, between Bohumín and Chałupki, the Oder itself becomes the Czech–Polish border for a short stretch, until the Olza joins it between Bohumín and Gorzyce at about 190 m above sea level; below that confluence the river runs wholly in Poland. The 89 km Olza, which rises in the Silesian Beskids, forms two stretches of the state border totalling 25.3 km. In July 1997 the flood spread rapidly from Chałupki down to Racibórz.
Racibórz, Kędzierzyn-Koźle and Opole: The Flood of 1997
The upper Polish Oder flows through Upper Silesia past Racibórz, Kędzierzyn-Koźle and Opole. In July 1997 it was the centre of what Poles call the Millennium Flood (Powódź tysiąclecia). Two bouts of rain, on 3–10 July and 17–22 July, dropped 300–600 mm on southwestern Poland and the northeastern Czech Republic, several months’ rainfall in a few days, as a Genoa low moved from northern Italy and stayed over southern Poland for a long time. Water levels rose 2–3 m above previously recorded averages. The flood killed 114 people, 56 of them in Poland and 50 in the Czech Republic, and caused damage estimated at $4.5 billion. Racibórz was devastated.
The response is on the river today. Near the town, the Racibórz Dolny flood-control reservoir opened in 2020 at a cost of about 2 billion złoty. It can hold 185 million m³ of floodwater. During the Central European floods of 2024 it played a crucial role in protecting Racibórz, Opole and Wrocław.
At Kędzierzyn-Koźle the Oder becomes a working waterway. The Gliwice Canal, built in 1935–1939, climbs 41.6 km from here to the port of Gliwice in the Upper Silesian industrial region, and Koźle is the upstream limit of navigation on the Oder. The canal is 38 m wide and up to 3.5 m deep, overcomes a height difference of 43.6 m through six locks, and is open from 15 March to 15 December. Kędzierzyn-Koźle itself, at the confluence with the Kłodnica, is a major river port and a centre of the chemical industry. Opole itself, which became the capital of Upper Silesia in the Middle Ages, sits on the river’s banks further downstream.
Wrocław’s Islands and the Canalised Upper Oder
Wrocław, the largest city on the Oder and the capital of Lower Silesia, grew from the river’s islands. A West Slavic tribe, the Ślężans, built a fortified settlement on Ostrów Tumski (Cathedral Island), once an isolated islet between branches of the Oder; the town then spread to Sand Island (Wyspa Piasek) and only later to the left bank. Wrocław became the seat of one of Poland’s oldest bishoprics in 1000, and the cathedral on Ostrów Tumski is still the city’s skyline from the water.
The river through and above Wrocław is heavily engineered. In the late 19th century the main stream was canalised at Breslau, as Wrocław was then called, and from the mouth of the Eastern Neisse to the Kłodnica Canal, a distance of over 80 km; the work was finished in 1896. The upstream section is still canalised and takes barges up to CEMT Class IV between the industrial sites around Wrocław. Below the city the Oder runs freer, past Brzeg Dolny, Ścinawa, Głogów and Nowa Sól, through a broad valley in Lower Silesia and Lubusz Land.
From the Neisse Mouth at Ratzdorf to Frankfurt and Słubice
North of Guben and Gubin, between Neißemünde-Ratzdorf on the German side and Kosarzyn on the Polish, the Lusatian Neisse flows in from the south. From this confluence the Oder becomes the Polish–German border for 187 km. The line was agreed in principle at the Tehran Conference in 1943 and imposed at Potsdam in 1945, when the German lands east of the two rivers passed to Poland; the remaining German population, about 8 million people, was expelled. East Germany confirmed the border in the Treaty of Zgorzelec in 1950, West Germany accepted its inviolability in the Treaty of Warsaw in 1970, and reunified Germany and Poland signed a treaty recognising it in 1990.
The border split towns in two. At Eisenhüttenstadt the Oder–Spree Canal, dug in 1887–1891, leaves the river for the Spree and Berlin. A little further north, Słubice on the Polish bank was the Dammvorstadt suburb of Frankfurt (Oder) until 1945; today the pair forms a cross-border agglomeration of about 85,000 people. Just downstream lies Lebus, the medieval Lubusz, capital of the Lubusz Land, which chroniclers called “the key to the Kingdom of Poland” and which gained a bishopric in 1125.
Kostrzyn, the Warta and the Drained Oderbruch
At Kostrzyn nad Odrą the Oder receives the Warta, its largest tributary, about 808 km long with a basin of 54,529 km². The Warta is navigable from Kostrzyn to Konin and offers smaller vessels a route to Poznań and Bydgoszcz.
West of the river lies the Oderbruch, about 60 km long and 12–20 km wide, an area of some 920 km² that slopes from 14 m above sea level in the southeast to just 1 m in the northwest. Until the 18th century the Oder wandered across it in several channels and flooded it several times a year. Embankment work began in 1735, and between 1746 and 1753, on the initiative of Frederick the Great, the river was diverted into a new, straight channel near Küstrin (Kostrzyn); drainage continued until 1762. The marsh became farmland, while the 17% of the Oderbruch that is now in Poland kept its wetland character. In 1945 the Oderbruch saw two months of heavy fighting as Marshal Georgy Zhukov’s 1st Belorussian Front advanced through it towards Berlin. At Hohensaaten the Oder–Havel Canal of 1914 gives Berlin its second link to the river.
Lower Oder Valley, Szczecin and the Three Mouths to the Baltic
Below Hohensaaten the valley widens into the Lower Oder Valley International Park, created in 1992 by the German and Polish environment ministers. Its core of 165 km² combines Germany’s Lower Oder Valley National Park (105 km²), with an information centre at Criewen, and Poland’s Lower Odra Valley Landscape Park (60 km²). With adjoining reserves the protected area reaches 1,172 km². On the flat western shore, dikes are opened in winter and spring so the river can flood its old meadows, then closed again in April. Black storks, aquatic warblers and corncrakes nest here, and otters and beavers live along the channels. On the Polish side, the Międzyodrze between the West and East Oder, from Widuchowa down to Szczecin, is a network of polders built between 1849 and 1932, with 33 km of canals and 177 km of levees.
The whole river has also suffered. In summer 2022 more than 100 tonnes of dead fish were removed from the Polish Oder and a further 35 tonnes from German stretches. A European Commission report of February 2023 concluded that the direct cause was toxins from the golden alga Prymnesium parvum, whose bloom was made possible by discharges of saline industrial wastewater into the river on the Polish side.
Past Gryfino the river reaches Szczecin, whose seaport handled about 11.2 million tonnes of cargo in 2022. Run jointly with Świnoujście, it forms the sixth-largest port complex on the Baltic. Below Police the main branch enters the Szczecin Lagoon, 687 km² in area and on average only 3.8 m deep, shared by Poland and Germany. The Oder supplies 94% of the water entering it, about 17 km³ a year, and that water stays in the lagoon for about 55 days before leaving through three straits to the Bay of Pomerania.
The Świna, between the islands of Usedom and Wolin, carries most of it, past Świnoujście. The Peenestrom runs west of Usedom past Wolgast in Germany, and the Dziwna east of Wolin past Kamień Pomorski and Dziwnów. To compare this journey with Germany’s other great river to the North Sea, see our Elbe River guide; for the sea at the end of it, read about the Baltic Sea, and for the frontier the Oder helps to draw, our guide to the countries that border Poland.