A high cliff separates this small lake from the open sea, to which it is connected by an approximately 80-meter-long tunnel. The geological curiosity benefits divers, tourists and fishermen alike. Divers are often accompanied above their heads by fishermen's excursion boats and kayakers, as a drive through the tunnel is a popular attraction. If the rock breakthrough appears to be relatively large above water, it is designed as a narrow gap below the surface, initially six meters deep. The bottom of which drops to about 30 meters towards the sea. This varied silhouette of the tunnel walls with rocky outcrops and overhangs forms the framework for the spectacular view of the bright royal blue of the sea. After the exit, the path leads along steep vertical indentations to the individual turning point. The vegetation consists of algae, bog animals and various sponges.