The Capo Carbonara Marine Protected Area, established in 1998, spans 86 square kilometres of southeastern Sardinian coast and ranks among the Mediterranean's most biodiverse marine reserves. Its boundaries enclose granite headlands, submerged shoals, and Posidonia meadows that support over 1,200 documented species, including loggerhead turtles, moray eels, and endangered dusky grouper. The reserve's strict zoning—ranging from no-entry sanctuaries to regulated tourism corridors—has allowed fish populations to recover at rates documented by the University of Cagliari's marine biology department since 2003. Villasimius, the reserve's administrative hub, sits at the eastern edge of the Gulf of Cagliari, where the Tyrrhenian Sea meets a coastline shaped by millennia of wind and wave action. Villasimius boat excursions depart from Porto Turistico, a sheltered harbour that replaced the old fishing jetty in 2005 and now accommodates vessels ranging from rigid inflatables to 12-metre catamarans. Most operators anchor at Secca di Berni, a shallow reef plateau 200 metres offshore, and Cala Caterina, a crescent bay whose granite cliffs drop vertically into water that remains gin-clear even in August. The marine park's protection extends to Isola dei Cavoli, a granite islet crowned by a 19th-century lighthouse, and the surrounding shoals where Mediterranean fan coral clings to rock faces at depths between eight and twenty metres. Visibility averages 25 metres during summer months, conditions that make snorkelling accessible to novices while offering enough topographic variation—swim-throughs, boulder fields, and vertical walls—to engage experienced divers. The reserve's tourism framework, revised in 2019, caps daily vessel numbers and mandates certified guides for all commercial excursions within Zone A, the core sanctuary area. This regulatory structure has made Villasimius a model for sustainable marine tourism in Italy, balancing ecological preservation with a visitor season that peaks between June and September. Southern Sardinia's coastal tours now draw researchers and photographers as often as leisure travellers, a shift driven by the reserve's success in rebuilding species richness and by the clarity of its waters, which allow unobstructed observation of fish behaviour and benthic communities. Boat operators in Villasimius favour early-morning departures, when wind speed remains below ten knots and sunlight penetrates the water column at optimal angles for underwater visibility. The combination of protected status, geological diversity, and seasonal weather patterns has positioned the area as a reference point for Mediterranean marine conservation, with monitoring data feeding into EU-wide biodiversity assessments. Visitors arriving at Porto Turistico in 2026 encounter a working harbour that doubles as a gateway to one of Europe's most rigorously managed coastal ecosystems.