Hi Lorna
We have done the Kkra falls but not with Viking. As others have said, to get the full ‘experience’ it is quite a walk down to the falls but generally easy with broad walks as shown. There are a couple of places where it can be a bit dodgy! The falls are now viewed from a distance, you can no longer paddle/ swim in the water 😞. They are beautiful. Again as has been said, the walk back to the meeting place is shorter in time but involves a lot more short, sharp uphill (steps) than going down. I think you can go back the way you come down but due to time constraints it may not be feasible.
Croatia is a beautiful place, there are so many wonderful places to visit.