© OPIS Zagreb, Shutterstock
With two saltwater lakes and a crumbling monastery, this national park is Mljet’s biggest tourist draw.
Mljet is one of the most attractive islands in the whole Adriatic. Despite being unusually beautiful, and entirely unspoiled by deforestation (it was never ruled by Venice, hence also the lack of towns of any size), it has hitherto remained relatively unvisited – though with the fast connection from Dubrovnik more people are coming every year. Nonetheless, the island is easily big enough, at over 100km², to absorb many more visitors without getting overcrowded.