National Plitvice Lakes Day is observed in Croatia every April 8, celebrating the Plitvice Lakes National Park, a UNESCO World Heritage Site since 1979. The park, founded on April 8, 1949, is renowned for its stunning lakes arranged in cascades, waterfalls, and caves formed by the Korana River in a heavily forested karst region. The name "Plitvice" was first recorded in a document from 1777. This ecological observance highlights the park's diverse flora and fauna, attracting over 1 million visitors annually. The day commemorates the park's official founding and serves as a reminder of the importance of preserving this natural landmark.