Europe’s third-largest lake drains west to the sea
Vänern blankets 5,655 square kilometres of Sweden—largest lake in the country and the European Union, third in Europe after Ladoga and Onega. Alone among Sweden’s top ten lakes it empties westward through the Göta älv toward Gothenburg and the Kattegat.
The surface sits forty-four metres above sea level, averaging twenty-seven metres deep and plunging to about 106 metres at maximum. Roughly twice Luxembourg’s area, the lake straddles Götaland and Svealand, with the western basin called Dalbosjön. Klarälven enters near Karlstad; Gullspångsälven, Byälven, and Norsälven add more water before the Göta älv carries outflow southwest toward the North Sea–Baltic hinge at the Kattegat.
Quaternary ice sculpted the southeastern depression by stripping Paleozoic sediments and re-exposing the Sub-Cambrian peneplain. About ten thousand years ago meltwater briefly made a Swedish strait between Kattegat and the Gulf of Bothnia; isostatic rebound left Vänern as a freshwater remnant of that drowned corridor. Norse memory kept the water fierce: a sixth-century battle on its ice appears in sagas and in Beowulf, which places a dragon’s mound near the lake. Snorri’s Prose Edda land-gift tale about Gefjon was probably first told of Vänern, not Mälaren.
Towns have lived for centuries on fish and on cheap water transport west to the sea. Djurö National Park protects an archipelago mid-lake; Kinnekulle’s plateau offers views roughly 270 metres above the surface. Monitoring in 2002 found overall quality stable but slightly reduced clarity from algae, with some bays eutrophic. Open-water counts can reach about 2,600 smelt per hectare in eastern Dalbosjön, with vendace second—bounty that locals and officials now try to shield from pollution and altered tributaries. That mix of myth, meltwater, and modern fisheries keeps Vänern more than a blue blot on the national map.
Source: Vänern
