- ...that Spreuerhofstraße in Reutlingen is the world's narrowest street? It ranges from 31 centimetres (12.2 in) at its narrowest to 50 centimetres (19.7 in) at its widest.
- ...that in 2017 a diver discovered Europe's first cave fish in the Danube-Aach system? Researchers at the University of Konstanz carried out genetic studies of the loach which showed that the species had only been living in the cave for 20,000 years.