|Arvenbühl near Amden.
|no restrictions 
|L=1,920 m, 1,800 m underwater.
|cave not accessible
|Emil Zopfi (): Churfirsten - Über die sieben Berge, Bergmonografie. 192pp, 149 images, 17x24 cm, Hardcover. ISBN 3-909111-22-X.
|As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then.
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|first exploration of the entrance.
|first cave diving attempt by members of the SAC Bern, which explored 100 m of underwater cave, one diver dies.
|cave diving attempt by divers from Winterthur, one diver killed.
|members of the diving club Glaukos from Zürich reach 220 m.
|members of the Zürcher Speleoclub and the Unterwassersportzentrum Zürich form the Arbeitsgemeinschaft Rinquellenforschung.
|first dive by Jochen Hasenmayer, reaches 930 m.
|diving attempt by Jochen Hasenmayer filmed by the ZDF, the German television.
|river cave behind the submerged part explored.
|end of exploration.
The Rinquelle (Rin Spring) is the biggest karst spring of the karst area Churfirsten-Säntisgebiet. The spring is part of a spectacular ensemble of a 600 m high drop of the Serenbach (Seren brook). With three subsequent drops the waterfall of the small river is not the highest single waterfall, but still one of the highest waterfalls in Europe. At the foot of the steep cliff the Serenbach forms a gorge, the Serenbachschlucht. Soon after it flows into the Walensee. The Rinquelle is located at the foot of the drop, the lowest segment of the waterfall. 48 m high in the vertcal cliff is a cave entrance, where an enormous beam of water leaves the mountain.
Locally the biggest spring, the Rinquelle is also one of the biggest karst springs in Switzerland. During snow melt and after high precipitation it has a yield of 10 m³/s. But as typical for karst springs, it depends very much on the weather, and during dry periods, or in winter when all water forms snow, the spring has a very low yield or falls dry. During those times cave divers are able to explore the extensive cave system behind.
The name Rin is rather strange. Locally a river is named Rin, but also the local dialect version of the nearby Rhine river is Rin. There is a legend, that the Rhine looses water which reappears here, but so far there is no proof at all, that some water originates from the Rhine. The catchment area seems to be the Churfirsten region which has a size of about 50 km².