Blautopf

The Blautopf is a funnel-shaped pool about 40 metres across at the foot of the Swabian Jura, and its colour looks almost unreal: an intense, milky cobalt that turns greener on some days. The effect has a physical cause. The water carries extremely fine particles of dissolved limestone that scatter blue light, while its depth of 21 metres swallows the other colours, so the basin glows as if lit from below. Out of it flows the little river Blau, which runs some 14.5 kilometres before joining the Danube.

The pool is the only visible opening of a vast cave system. Water collected across roughly 160 square kilometres of the Jura surfaces here, on average about 2,300 litres a second, but after heavy rain the discharge can swell more than tenfold. Divers first descended in a helmet suit in 1880 and reached the bottom of the funnel in 1957. From 1985 Jochen Hasenmayer pushed through the flooded passages beyond, and later cave-diving teams found dry chambers on the far side of the sumps, among them the vast hall named Apokalypse, discovered in 2006 and about 170 metres long. Surveyed passages behind the Blautopf now run for well over fifteen kilometres, making it one of the longest cave systems in Germany. Diving in the spring itself is not open to the public.

The pool has its own legend. In Eduard Mörike's novella The Stuttgart Hutzelmännlein, the beautiful water-nymph Lau is held captive in the Blautopf, and the story weaves in local folklore, including a Swabian tongue-twister about a lump of lead lying in the pool. On the bank a hammer mill, founded in the early nineteenth century and powered by the spring, still stands, and a few steps away rises Blaubeuren Abbey, whose church holds a carved high altar of 1493 from the Ulm school. Together, spring, mill, abbey and the steep wooded valley make one of the most complete small landscapes of the Swabian Alb.

Getting there

The Blautopf lies on the edge of the old town of Blaubeuren, about 16 km west of Ulm; Klingenstein, the nearest larger settlement listed nearby, is about 9 km away. From Blaubeuren railway station it is roughly a 25-minute walk through the old town. The nearest airport is Memmingen (FMM), about 58 km to the south.