Geocahce is available only during every vacation: here's information when

You will find geocache in tent base, just ask base keeper for geocache. Some items can be used on a base (boiling water, and mugs are available there). After writing something in logbook, you can also write/draw something in Base's Chronicle, and ask for the stamp (almost like letterbox ;-)). Geocache is available only in vacations, when tent base is open.

geocache is also registered at opencaching.pl