The lake lies within Sweden's agricultural heartland and is surrounded by forest. It fills part of a broad basin that was created over 500 million years ago when the hard volcanic rocks of the region subsided as a result of movements of the Earth's crust.
The waters of Lake Vänern reach a depth of 98 meters (320 feet), although they are much shallower than this in many places. The basin is bisected by a ridge of hills, which appear on the lake as the northern and southern peninsulas of Värmlandsnäs and Kalländshalvö, and an archipelago of islands.
The lake is cradled by low hills and mountains on the south and east. Rivers and streams flow into Vänern on one side and into the Baltic Sea on the other. Rolling hills to the north rise toward the mountains that dividing Sweden from Norway. This is where the large rivers that feed Vänern, such as the Klarälv, originate.
Lake Vänern's only outlet is to the south along the Götaälv River. The waters of the river have cut a path through a ridge of gneiss, an ancient rock that is hardened by intense temperature and pressure. This ridge drops more than 30 meters (100 feet) in just under 1.6 kilometers (1 mile), as it slopes toward the south. Lake Vänern's waters were diverted into a hydroelectric scheme during the first half of the 20th century. Until then, the lake emptied itself over the slope in the form of the impressive Trollhättan Falls.
The area around the lake is the home of rich and abundant wildlife, and it has been a focus of human activity for a very long time. The ancestors of the Goths founded the Swedish civilization here over 5,000 years ago.
The Göta Canal
In 1718, King Charles XII of Sweden commissioned a series of eight locks to be built around the falls so that boats could travel between Lake Vänern and Gothenburg on the North Sea coast. Work on the project was halted in the same year when the king died on the field of battle. Fresh channeling attempts were made in 1749. However, the Trollhättan Canal was not completed until 1800.
Nine years later, entrepreneur Baron Baltzar von Platen convinced the Swedish Parliament to sponsor a canal link between Lake Vänern and the Baltic Sea. This civil engineering feat was finished in 1832, and the total canal system from Gothenburg to Mem on the Baltic became known as the Göta Canal.
The canal leaves the eastern shore of Lake Vänern at Sjötorp and winds toward Lake Vattern, Sweden's second largest body of water. Lake Vattern has a north-south length of 130 kilometers (80 miles) and a maximum width of 30 kilometers (20miles). It is extremely clear, primarily because of the gravel-purified waters of the natural springs and turbulent mountain streams which feed it. The lakebed can be seen at depths of up to 10 meters (33feet). The lake averages 40 meters (130 feet deep), but is 128 kilometers (420ft) deep in some places.
Kinnekulle Mountain
Kinnekulle lies above Sweden's Lake District, between Lake Vänern and Lake Vattern. Its summit is a flat tableland, 14 kilometers (9 miles) long, 7 kilometers (4 miles) wide and 306 meters (1,004 feet) high.
The mountainsides of Kinnekulle rise in a series of flat steps or terraces, separated from one another by sheer cliffs and differing vegetation. On one terrace there is bleak moorland, yet the next is covered by forest.
The change in vegetation is due to the nature of the underlying rock. Around 500 million years ago, the hard gneiss rock of the region subsided, and the land was covered the waters of the sea. Over millions of years, mud, sand and the organic remains of crustaceans, algae and fish, fell to the bottom of the sea and formed layers of sedimentary rock.
Around 200 million years ago, the land rose up from the sea bed, and volcanic lava welled up through vents in the Earth's crust, settling over local areas of sedimentary rock. Erosion removed softer, exposed layers of rock and left behind stepped tablelands, or mesas, of which Kinnekulle is the largest and geologically the most recent.
Each steppe is composed of a different combination of sedimentary, gneiss and volcanic rock - hence the variation in vegetation which grows on them.