Lake Constance - facts & figures

Constance (lighthouse) lat. 47°39' north, long. 9°10' east; Bregenz (lighthouse) lat. 47°30' north, long. 9°44' east.

Mean water level: 395 m/1,296ft (with fluctuations, so far unexplained, unconnected with seasons or weather conditions). This change of water level, which occurs at regular intervals in calm weather, resembles the ebb and flow of the sea, yet occurs 26-38 times in 24 hours and varies only a few centimeters.

Although the borders between the countries neighboring Lake Constance are not distinct, the respective areas are approximately as follows: Germany 55%, Switzerland 34% and Austria 11%. Total area: 545 sq. km/210 sq. mi (Obersee and Überlinger See together 480km/185 sq. mi, Untersee 65 sq. km/25 sq. mi).

Greatest length: between Bregenz and Stein am Rhein 76km/47mi (as the crow flies 69km/43mi).

Between Bregenz and the mouth of the Stockacher Aach 63km/39mi; longest direct line over water, from Hard to near the mouth of the Aach, 60km/37mi. Between Bregenz and Constance 46km/28mi.

Greatest width: between Kressbronn and Rohrschach 14.8km/9mi.

Greatest depth: in the Obersee (between Fischbach and Uttwil) 252 m/827ft, in the Überlinger See 147 m/482ft, in the Untersee 46 m/151ft (Zeller See 26 m/85ft, Gnadensee 22 m/72ft). New depth measuring works are in progress.

Circumference at half-tide level: total 263km/163mi, of which 168km/104mi (64%) are in Germany, 69km/43mi (26%) in Switzerland and 26km/16mi (10%) in Austria.

Average volume of water: total 48,430million cu. m/1,710,163million cu. ft, Obersee and Überlinger See together 47,600million cu. m/1,680,756million cu. ft, Untersee 830million cu. m/29,307million cu. ft.

Mean high water (end June/beginning July) 440 cm/173.2 inches (highest recorded, beginning September 1817, 623 cm/245.3 inches). Mean low water (end February) 280 cm/110.2 inches (lowest recorded this century, end March 1972, 237 cm/93.3 inches).

Visibility from surface: annual average 7.50 m/25ft (in January down to 12 m/39ft).