A heads up - Plitvice National Park is now selling online tickets, and they advise to buy in advance, though there will still be some tickets for sale each day at the park.

This is to avoid overcrowding and control the number of people in the park at any one time, so it is a good thing. I think since this is very new there will probably be some disappointed people at the park this summer.

You purchase the tickets here, and they send a voucher to exchange for paper tickets at the park. It took me a few tries before I was finally successful.
https://ticketing.np-plitvicka-jezer...ndex.aspx?l=EN

Thanks for posting this information, rialtogrl!
Online reservations should make visiting the park much easier -- at least once people know they need to do so.

Well, you still need to exchange the voucher for actual tickets, so we will see how easy that is.

But not overcrowding the park = Awesome Times Infinity

Now if they would just ban selfie sticks and tripods, we would be all set!

I used this service. I got the voucher several days after purchasing the tickets online. When I looked at the voucher they had assigned me a time to enter the park. The assigned time was not going to work so I got back to them and asked for a change in the time or cancellation. I did not realize that you could not still purchase tickets that day. Fortunately, they changed the time to first thing in the am which is what I asked them to do.
I was notified of this service by our accommodations there, Plitvice Miric Inn. I did not realize that you could not still purchase tickets that day. The email sent to me said you could still purchase that day.

Yes, I put in the date and time slot, but I gather something happened because I was assigned at 15:00 -17:00 as the time to pick up my tickets. Perhaps I did something wrong. Just happy I got what I wanted in the end.