Erdbachhöhle bei Erbach, Special Area of Conservation in the Odenwald, Hesse, Germany

Erdbachhöhle bei Erbach is a natural passageway formed through limestone, stretching roughly 400 meters beneath the Odenwald landscape. Water flows through the system year-round, shaping the passages and creating an environment separate from the world above.

The site was designated a natural monument in 1937, recognizing its geological value early on. This protection allowed researchers to study the formations and the life within them over the following decades.

Scientists regularly study the 104 specialized animal species inhabiting the cave, including rare spiders, pseudoscorpions, harvestmen, woodlice, and snails.

The cave is not open to visitors and its entrances have been secured with closures since 2014; the Erdbach disappears into several holes at the foot of a rock wall near the Erbach sports park. The stream reappears about 200 metres north near the Stockheimer Mühle in Michelstadt-Stockheim. Inside, the temperature stays between 8 and 9 °C with humidity above 90 percent.

Water entering through different openings reappears roughly one hour later at another spot in the system. Researchers confirmed this timing by tracing dye through the underground passages.