Photo - Hohlsteinhöhle
© Tsungam · CC BY-SA 4.0, https://creativecommons.org/licenses/by-sa/4.0/ · Wikimedia Commons · https://commons.wikimedia.org/wiki/File:Schlangen_-_2014-07-31_-_Hohlsteinhoehle_(13).jpg
Source: Geotopkataster Nordrhein-Westfalen (Geologischer Dienst NRW) (ogc-api.nrw.de), modified. Data licence Germany – attribution – version 2.0 (dl-de/by-2-0), https://www.govdata.de/dl-de/by-2-0 Geowissenschaftliche Daten: INSP-GeotopeinNRW @ Geologischer Dienst NRW · data as of 2026 · Contains information from Grottocenter (Wikicaves), grottocenter.org, made available under the Open Database License (ODbL 1.0, https://opendatacommons.org/licenses/odbl/1-0/), modified. · length · obtained 2026-11-13 · https://grottocenter.org/ui/entrances/23593 · data as of 2026 · The derived data is available on request under the ODbL: [email protected]