Höllgrotten, Show cave in Menzingen, Switzerland.

The Höllgrotten is a limestone cave system in Menzingen with multiple chambers connected by narrow passages, displaying stalactites, stalagmites, and small underground lakes. The passages guide visitors through different levels and room types that vary in size and appearance.

Tufa quarrying for the Bonstetten railway tunnel lining exposed the first grotto in 1863, and extraction was halted to protect it. In 1885 cantonal councillor Josef Leonz Schmid ordered a tunnel to drain the underground lake into the Lorze; the caves opened to the public in 1887. Further sections were found in 1892 and 1902, and in 1903 Schmid bought adjoining land to unite the whole system.

The name Höll comes from the old word Hell, meaning a forest clearing in the Lorzentobel; the ravine's remoteness later gave it a darker sense. Around 1860 pastor Johann Josef Zehnder of Neuheim tried in vain to talk the locals out of the name. When the grottoes were found in 1863, many saw demonic forces at work, and the dripstone shapes struck them as magical.

This cave is typically open from April through October, with guided tours available throughout these months. Sturdy shoes are recommended as pathways are wet and some passages are tight or low-ceilinged.

The cave contains both tufa and travertine deposits, creating two distinct types of mineral formations with different appearances and textures. Visitors can observe how these different deposits form separate visual zones throughout the passages.