The Aachtopf is Germany's biggest spring in terms of production, 8,500 liters per second on average. It is a karst spring which is located south of the western end of the Swabian Jura, near the town Aach , Baden-Württemberg. As a typical karst spring the production depends very much on the season and the weather but it never falls dry.

The name Aachtopf is built of Aach, the name of the river which springs here, and Topf which translates bowl and is commonly used for round, bowl-shaped springs. The Aach is flowing southwards and soon merges with the Rhine. The spring is the southern end of a cave system which transports water from the western end of the Swabian Jura. Most of the water is originally Danube water which sinks near Immendingen and near Fridingen . The strange fact is, that Danube water flows eastwards and disembogues into the Black Sea, whereas Aach and Rhine flow northwards to the North Sea.

The karst spring is connected to a huge cave which runs northwards. As it is completely water-filled it is explored only 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 meters, otherwise it would probably be several kilometres in length. A local caving club was formed to find this cave by digging a shaft behind the collapse. Until now the cave has not been found.

The Aachtopf is a favourite weekend destination and very romantic. It is not possible to see the cave.

External links

• Achtopf More background info on the karst spring.