The keyhole cave is not a show cave. Caving in the arbor area requires great experience, fitness and climbing skills. The entrance of the keyhole cave is located at 1274 m altitude, behind an artificially created platform is a rather inconspicuous cave entrance with opening to the north in a grassy rocky about 40 m high steep slope.
The total depth measured at that time was 141 m, the total length of the measured corridors at about 1390 m. The largest horizontal extent 210 m, the maximum overlap at approx. 177m. Through further explorations and research until today, some, so far undocumented corridors and vents could be opened, information can be found u.A. in the documentation (Müchner Cave History II of 2004) of the Munich Caves Association e.V. In 1963, the narrow water-bearing passage below the treasure chamber was followed to another 30 m, the total depth of the cave has since been given as 156 m. Between 1972 and 1975, the cave plan with "new land" in the Stanglschlot, Hexenschlot, Dom im Riesenversturz, Hohe Kluft and Landregenhalle was extended to include previously undocumented cavities.
The name of the cave is derived from the second passage section in the entrance area, whose shape resembles a large keyhole (pressure pipe with erosion channel).