Mljet became Yugoslavia's first marine protected area in 1960, seventy years after the Austro-Hungarian Empire logged its last Aleppo pine. The western third of the island — two interconnected saltwater lakes, a Benedictine monastery on a forested islet, and twenty-four square kilometres of Mediterranean maquis — was drawn into conservation when the Yugoslav Academy mapped endemic flora that survived nowhere else on the Adriatic. The park boundary follows the 12th-century property line of the Republic of Ragusa, which planted olives and vines but left the interior forest untouched. That restraint preserved a canopy dense enough to shade the lakes even at summer midday. Today the park anchors the quietest sector of Croatia's island tourism. No cars enter the conservation zone. Visitors cycle the perimeter track or board the solar-powered catamaran that crosses Veliko Jezero to St. Mary's islet every half-hour. The Benedictine church, founded in 1198, was abandoned in 1808 when Napoleon dissolved the monastery; its frescoes, whitewashed during Turkish raids, were uncovered in a 1958 restoration that revealed Romanesque stonework beneath Habsburg plaster. The adjacent refectory now holds a small conservation archive and a café that sources honey from the island's four remaining beekeepers. The lakes themselves are geological anomalies. Veliko Jezero reaches thirty-seven metres at its deepest trough, fed by submarine karst springs that cycle seawater through fissures in the limestone bedrock. Salinity fluctuates with tide and season, supporting both marine and brackish species — grey mullet school near the surface while sea urchins cling to submerged Roman masonry. The smaller lake, Malo Jezero, warms to twenty-six degrees by mid-June, five degrees above the open Adriatic, turning it into a natural swimming basin ringed by stone pines. A narrow channel links the two bodies of water, bridged by a Roman-era causeway that was widened for bicycles in 1974. The forest floor is limestone pavement, fractured into clints and grykes that trap rainwater and nurse wild orchids. Mljet lies ninety minutes southeast of Dubrovnik by catamaran, the last substantial landmass before the open Mediterranean. The park operates year-round but closes the solar boat service in November when visitor numbers fall below twenty per day.