The Algarve's limestone coastline has been carved by Atlantic swells for six million years, creating the honeycomb of sea caves and natural arches that define the shore between Albufeira and Carvoeiro. Benagil Cave, the region's most celebrated formation, formed during the Miocene epoch when softer sedimentary layers eroded faster than the cliff face above, leaving a cathedral dome pierced by a circular skylight. The cave's interior chamber spans twenty-three metres, its ochre walls striated with iron oxide and calcium deposits that shift from amber to rust depending on the angle of morning sun. The same coastal shelf that sculpted these grottoes also sustains one of Europe's most reliable populations of common bottlenose dolphins. Marine biologists estimate that between eighty and one hundred twenty individuals patrol the waters off Albufeira year-round, drawn by the upwelling currents that bring sardines, mackerel, and cuttlefish close to shore. Pod sizes average five to twelve dolphins, though solitary males and nursing females with calves are frequently sighted within two kilometres of the marina. Peak activity occurs between dawn and mid-morning, when the animals hunt in coordinated arcs before retreating to deeper water as boat traffic increases. Dolphin and cave trip Albufeira departures originate at Marina de Albufeira, a sheltered basin constructed in 1986 that now serves as the embarkation point for the majority of coastal excursions along this twelve-kilometre stretch. The marina's south-facing orientation provides natural protection from prevailing northwest winds, allowing operators to maintain consistent schedules even during spring and autumn swells. Most vessels follow a clockwise route, heading west past Praia dos Pescadores and the red cliffs of São Rafael before reaching the cave-dense corridor between Praia da Marinha and Praia de Benagil. The return leg typically tracks closer to shore, passing the natural archway at Arco de Albandeira and the twin stacks at Praia da Mesquita. The confluence of geological drama and marine biodiversity has made Albufeira's coastal waters a focal point for sustainable tourism policy in Portugal. Regional authorities introduced seasonal speed restrictions in 2019 and established exclusion zones around known dolphin feeding grounds, measures that reduced boat-strike incidents by forty-one per cent within two years. Tour operators now coordinate departure windows and share real-time sighting data via radio, a collaborative approach that improved encounter rates while reducing cumulative engine noise in sensitive habitats.