I recommend the tour upwards, around the Ossiacher Tauernsee and the same route back. The direction of view changes on the descent, so go both directions (or what experienced hikers …
In the upper part you cross a riverbed that is about eight meters deep, and you have to carry your bike. Anyone who doesn't like that can access the trail via the forest road further down.
It is really quaint in this gorge. Highly recommended on hot days because it is almost always in the shade and the water creates a pleasant, cooling atmosphere.