Plitvice Lakes National Park is magical.
Rick Steve’s has a segment on the park in his Croatia show, which I have watched probably a dozen times, dreaming of walking the wooden pathways and seeing the wonders of the park in person. It did not disappoint. It is stunning. Amazing. Beautiful. Even in the rain.
We visited the park over two days, which is not necessary, but it allowed us to go in the afternoon (around 3 pm), after the crowds had essentially cleared, and then again the next morning at opening (8 am). We slept at a nearby sobe (10 minutes walk) to make sure we could arrive right when the park was opening. This ended up being a really good decision, as that first afternoon it stopped raining just long enough to spend three hours wandering the park. There were still crowds at the lower lakes, which was stressful as the boardwalks were completely flooded in some places and people were (unsuccessfully) trying to keep their feet from getting wet. But once we strayed from the large waterfall, we had the paths mostly to ourselves.
The next morning it felt like we were the only people in the park. It was pretty wet and foggy, but not enough to spoil the experience. We spent another 3 hours wandering around the upper lakes before catching the 1 pm bus back to Zagreb. Once again, we really lucked out and as the thick, cold fog rolled in around noon, we were on our way out.
There are lots of forums on how to avoid crowds at Plitvice. Our answer? Go when the weather is just a little crappy. Not enough that you will be miserable, but enough that other, less hearty people, may be deterred. If you embrace, accept, and prepare to be a little wet and cold, you may be rewarded by empty paths and a magical fairyland all to yourself.