6. Santorini, Greece
Santorini, famous for its stunning sunset views and white-washed buildings, has become overrun with tourists in recent years. The small island can feel overcrowded, especially around Fira and Oia, where the streets are packed with travelers.
Cruise ship days are particularly challenging, as thousands of tourists flood the island at once. Visiting during the off-season can offer a quieter, more relaxing experience.