If you want to see Croatia in 4 days, it's best to plan your itinerary carefully. Day 1 can be spent exploring Dubrovnik's Walls, followed by a visit to Elaphiti Islands on Day 2 and Mljet Island on Day 3. Finally, on Day 4, end your trip at one of the many beautiful beaches in Dubrovnik. Alternatively, you can take a guided tour from various tour operators like TourRadar, Tour Vacations to Go, and G Adventures to make the most of your trip.