This leads to a *deep* rabbit hole: The cave entrance is marked as a dive spot, many of those in Switzerland have a link to http://www.dive-links.com/, which has not been working since November 2017 (https://web.archive.org/web/20171130064931/http://www.dive-links.com/). There are +270 links in Switzerland to the site, which thus needs a larger clean-up: https://osm.li/TFZ