On the surface, these two UNESCO-listed, waterfall-rich national parks might seem quite similar. Certainly, you might find it unnecessary to visit both on the same trip. Your decision might be made easier by proximity, if you're staying in a city that's closer to one or the other. Plitvice Lakes National Park is by far the most visited of the two, and the most iconic, but visiting Krka can help you avoid some of the crowds.