DRAVA CYCLING ROUTE
The cycling route along Drava runs through 4 countries (Italy, Austria, Slovenia, Croatia) and has a total length of about 710 km. The route begins right next to the source of Drava on Toblach Field (Toblach) in Italy. It then continues through Austria, Slovenia, and finally Croatia (where the route is not yet fully arranged and marked.
You can find more information here.