The Gründelsloch is a fractured karst spring, which was created in 1611. The karst fissure spring, surrounded by old legends, pours out about 15,600 liters of water per minute, making it Thuringia's strongest spring. The almost circular water basin of approximately 22 meters in diameter and 9 meters deep is surrounded by many tall trees and bushes. Something fascinating, however, is the play of colors of the crystal clear spring water in the sunshine.

In the center of the funnel there are several openings 25-30 cm in diameter, from which the water wells. It looks here as if the sandy bottom is boiling. However, the water has a constant temperature of 10 to 11 degrees Celsius. From the high lime content of the water (71 German degrees of hardness) it may be concluded that it must have already traveled a long underground path through the calcareous rock of the Hainleite before it comes to light here.

The Gründelsloch is enclosed by a nature trail and is an ideal starting point for a hike.