Lake Constance is the third-largest freshwater lake in Central and Western Europe in surface area and the second-largest in volume.
Lake Constance was formed by the Rhine Glacier during the ice age and is a zungenbecken lake.
The Roman geographer Pomponius Mela was the first to mention the lakes around 43 AD, calling the upper lake Lacus Venetus and the lower lake Lacus Acronius.
In Lake Constance, there are ten islands that are larger than 2,000 m². The largest is the island of Reichenau in the Untersee.
The lake lies where the countries of Austria, Germany, and Switzerland meet. There is no legally binding agreement as to where the borders lie between the three countries.
In late August 2005, heavy rain raised the level by more than 70 cm in a few days. The rains caused widespread flooding and washed out highways and railroads.
Around 45 species of fish live in Lake Constance.
Lake Constance refers to three bodies of water on the Rhine at the northern foot of the Alps: the Obersee or Upper Lake Constance, the Untersee or Lower Lake Constance, and a connecting stretch of the Rhine called the Seerhein.
The max length of Lake Constance is 39 miles, and the max width is 8.7 miles, with an average depth of 300 ft and max depth of 823 ft.
In 1963, the whole lake froze. This has not happened since then.