Hornisgrinde, Summit in Northern Black Forest, Germany.

Hornisgrinde is the highest mountain of the Northern Black Forest, a ridge about two kilometres long running roughly north to south at 1,164 metres. Its summit plateau carries the Grinden, treeless wet heaths, and a raised bog up to five metres thick. At the southern end stands the 23-metre Hornisgrindeturm of local red sandstone, built in 1910; at the highest point is the small signal tower, and a 206-metre radio mast of the Südwestrundfunk rises above the tree line.

A sandstone slab called Dreifürstenstein has marked the boundary meeting point of Baden, Württemberg, and the Diocese of Strasbourg since 1722. During World War II, German military forces used the summit for air defense operations, leaving behind remnants of those installations.

The name, recorded since 1605, probably means "ridge bearing a bog on its height", from Horn, miss and Grinde. The treeless Grinden heaths date from 15th-century forest clearance and grazing. A boardwalk of the Ruhestein nature conservation centre crosses the raised bog, reckoned at least 6,000 years old.

Visitors can use various hiking trails, with the most popular route from Ruhestein being roughly 11 kilometers long and involving considerable elevation changes. It is wise to wear sturdy footwear and be prepared for changing weather conditions, as the summit can be quite windy.

The summit plateau holds a raised bog up to five metres thick, reckoned at least 6,000 years old and naturally treeless, crossed by a wooden boardwalk on the Ruhestein nature centre's trail. The bare Grinden heaths around it came from forest clearance and grazing from the 15th century. Since 1992 the bog and the Biberkessel cirque wall form a 95-hectare nature reserve.