Dubrovnik-Neretva County dive sites

Mljet is reached by catamaran ferry from Dubrovnik, taking approximately 90 minutes, or from Korcula Island in about 50 minutes. During summer, multiple daily connections operate. The island has several small settlements with accommodation, though options are limited and advance booking is essential in peak season. The dive centre operates from Polace or Sobra. Some divers base themselves in Dubrovnik and take day trips to Mljet, though this limits dive timing flexibility. Liveaboard trips along the Croatian coast frequently include Mljet stops.

Mljet's southern coast faces the deepest section of the Adriatic Sea, where the channel between the island and the Italian peninsula exceeds 1,000 metres depth. This proximity to deep oceanic water produces several advantages for diving. The walls drop steeply and continuously from shallow reef to beyond recreational limits, the deep water circulation brings exceptional visibility often exceeding 30 metres, and the nutrient flow supports denser invertebrate growth including red coral at diveable depths. Most other Croatian sites are in the shallower northern or central Adriatic where conditions are less oceanic.

The Mljet National Park covers the western third of the island including its two saltwater lakes, but diving is regulated rather than prohibited. The national park marine zone has specific rules: diving must be arranged through authorised operators, anchoring is restricted to designated points, and some areas are closed seasonally. The best dive sites along the southern outer coast fall partially within and partially outside park boundaries. All operators on the island are familiar with current regulations and dive responsibly within the rules. Night diving requires special permission.