Plitvice Lakes

Plitvice Lakes need 1 full day: walking the wooden boardwalks among 16 intensely turquoise terraced lakes, connected by dozens of waterfalls. April-June and September-October are best, with fewer crowds than the July-August peak. It's mid-priced, with access controlled by time slots in high season. It's Croatia's oldest and most visited national park, a UNESCO World Heritage Site since 1979, and its lakes, formed by natural limestone and moss dams that keep growing and changing shape over time, shift color depending on light and minerals dissolved in the water.