The app "Out in the River" is an offer of the Environmental Education Center Treasure Island Kühkopf, in Hesse's largest nature reserve "Kühkopf-Knoblochsaue" in the Rheinaue in Darmstadt to go on a journey of discovery. The journey leads through QR codes on an adventure trail of less than an hour in the middle of the unique river landscape.
Further information is also hidden in the exhibitions of the Environmental Education Center in Hofgut Guntershausen.
So - load the app and off you go.