The Ria Formosa lagoon shifts position. Its barrier islands migrate eastward by several metres each year, redrawn by Atlantic currents that no engineer has managed to fix in place. Faro sits behind this moving wall of sand, sheltered from open ocean by five islands and two peninsulas across roughly 60 kilometres of coast. Every faro dolphin watching boat tour departs from inside that shelter and crosses out through a man-made inlet into deeper water. The lagoon was declared a Natural Park in 1987, protecting some 18,000 hectares of tidal channel, salt marsh and sandbank. Salt has been harvested here since Roman times; the rectangular evaporation pans visible from any Faro dolphin boat trip still supply flor de sal to Portuguese kitchens. The Romans built the port of Ossonoba on this shore. The Moors fortified it. The old town's Arco da Vila still frames a horseshoe arch beneath eighteenth-century masonry, and the cathedral behind it was rebuilt after the 1755 earthquake flattened much of the Algarve coast. Offshore, the water tells a different story. The continental shelf narrows sharply south of Faro, and upwelling along the Cape Santa Maria approaches brings cold, nutrient-rich water within reach of a morning sailing. Common dolphins (Delphinus delphis) travel here in pods that can exceed a hundred animals. Bottlenose dolphins hold smaller, more territorial groups closer to the inlets. Loggerhead turtles, ocean sunfish and, in summer months, minke whales pass through the same corridor. Operators running faro dolphin watching boat tour tours work under a national code of conduct that governs approach distance, engine speed and the number of vessels permitted around a single pod. The lagoon itself supports Europe's most significant population of purple swamphen and hosts around 20,000 wintering waders. Ninety per cent of Portugal's clam production comes from these mudflats. Ilha Deserta, the southernmost point of mainland Portugal, carries no permanent residents at all — a single restaurant, a boardwalk and eleven kilometres of empty sand. This is why marine biologists in the Algarve treat the water off Faro as a monitoring station rather than a backdrop. Sighting data collected on commercial sailings feeds regional cetacean records. A faro dolphin watching boat tour is, in that sense, an unusually well-documented stretch of Atlantic: catamarans, RIBs and speedboats all working the same channel between Cape Santa Maria and the shelf edge, logging what surfaces.