Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
's biggest natural spring
A spring—also known as a rising or resurgence—is a component of the hydrosphere. Specifically, it is any natural situation where water flows to the surface of the earth from underground...
, producing an average of 8,500 litres per second. Production varies seasonally and in response to the weather, but the spring never runs dry. The Aachtopf is a karst spring
A karst spring is a spring that is part of a karst system. That includes the underground drainage of a much larger area, which means that karst springs often have a very large discharge...
which is located south of the western end of the Swabian Jura, near the town Aach
Aach is a small town in the German state of Baden-Württemberg . Being situated close to Lake Constance and the Swiss border, it is mostly known for the Aachtopf — Germany's biggest natural spring in terms of production.-History:...
The name Aachtopf is compounded from Aach
(meaning water in Old High German
The term Old High German refers to the earliest stage of the German language and it conventionally covers the period from around 500 to 1050. Coherent written texts do not appear until the second half of the 8th century, and some treat the period before 750 as 'prehistoric' and date the start of...
); the name of the river created by the spring is in full the Radolfzeller Aach
The Radolfzeller Aach is a right or north tributary of the Rhine in the south of Baden-Württemberg .It is approximately 32 km long.- Course :...
can be translated as bowl
and is commonly used for round, bowl-shaped springs. The Radolfzeller Aach flows southward into Lake Constance
Lake Constance is a lake on the Rhine at the northern foot of the Alps, and consists of three bodies of water: the Obersee , the Untersee , and a connecting stretch of the Rhine, called the Seerhein.The lake is situated in Germany, Switzerland and Austria near the Alps...
, which empties into the Rhine
The spring marks the southern end of a cave system which transports water from the western end of the Swabian Jura. Most of the water is derived from the River Danube and is obtained where the latter river disappears underground at the Donauversickerung
(Danube Sink) near Immendingen
Immendingen is a town in the district of Tuttlingen in Baden-Württemberg in Germany....
Fridingen is a town in the district of Tuttlingen, in Baden-Württemberg, Germany. It is situated on the Danube, 10 km east of Tuttlingen, and 23 km west of Sigmaringen....
. Strangely, the Danube
The Danube is a river in the Central Europe and the Europe's second longest river after the Volga. It is classified as an international waterway....
flows eastwards into the Black Sea
The Black Sea is bounded by Europe, Anatolia and the Caucasus and is ultimately connected to the Atlantic Ocean via the Mediterranean and the Aegean seas and various straits. The Bosphorus strait connects it to the Sea of Marmara, and the strait of the Dardanelles connects that sea to the Aegean...
, whereas the Rhine
flows northwards to the North Sea
In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean. In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively...
. Therefore the water of the Aach
flows under the European continental divide. This is a relatively common feature of karst stream captures.
The karst spring is connected to a huge cave, which runs northwards. The cave is completely water-filled and can only be explored by cave divers. The first exploration was made by Jochen Hasenmayer, a famous German cave diver. Unfortunately, a collapse blocks the cave after a few hundred metres. The cave may continue for several kilometres beyond the other
side of the blockage. A local caving club was formed to find this "lost cave segment" by digging a shaft behind the collapse. At present, a continuation of the cave has not been found.
The Aachtopf is a favourite weekend destination and very romantic. It is not possible to see the cave because it is underwater and cave diving is extremely dangerous.
- Aachtopf More background info on the karst spring.