You will think about skipping Plitvice because it's an hour and a half inland and you came to Croatia for the coast. Don't skip it. Plitvice is one of the most extraordinary places in Europe and the journey from Zadar makes it genuinely accessible in a day.
Leave by 8am. The drive through the Lika region as you climb away from the coast is beautiful in its own right — the landscape changes completely from the limestone and pine of the coast to open hills, forest, and the dramatic karst terrain of the Croatian interior.
Arrive at the park as it opens. Buy your ticket online in advance — in summer they sell out days ahead and turning up without a ticket means turning around. Take the longer walking route rather than the boat-and-train option — the boardwalks through the lower lakes, with water cascading over travertine barriers on both sides, are the heart of the experience and deserve to be walked slowly.
The colour of the water is the thing nobody is prepared for. Not just blue or green — a constantly shifting spectrum of turquoise, emerald, and deep blue that changes with the light and the angle and the depth of the water beneath the boardwalk. It looks enhanced. It isn't. It's minerals and organisms and sunlight doing something that took thousands of years to arrange.
Spend at least four hours in the park — more if you can. Eat lunch at the park restaurant or bring your own picnic. Drive back to Zadar in the late afternoon, stop somewhere on the coast for a swim to close the day properly, arrive back in the city in time for dinner at Providur or Restaurant Terracotta.
Tips:
Book tickets online well in advance — this cannot be stressed enough. The park has strict daily visitor limits and sells out regularly in summer
Arrive when the park opens — the light is better for photography in the morning and the boardwalks are significantly less crowded before 10am
Wear waterproof shoes or sandals — the boardwalks are occasionally wet and spray from the falls reaches the path in places
The lower lakes are the most spectacular and the most visited — the upper lakes are quieter and worth including if you have the time
The drive back from Plitvice via the coastal road rather than the highway adds time but gives you a beautiful descent back toward the Adriatic as the sun drops — highly recommended on a clear evening