Marina de Lagos sits at the mouth of the Bensafrim River, where Portuguese caravels once set sail for West Africa and the New World in the fifteenth century. The same sheltered harbour now serves as the departure point for boat tour Lagos Algarve operators, whose vessels trace the limestone coastline that Prince Henry the Navigator would have seen before his death in 1460. The cliffs east of the marina rise in tiered strata of ochre and amber sandstone, sculpted by Atlantic swells into a sequence of arches, tunnels, and freestanding pillars that geologists attribute to marine erosion over the past six million years. Ponta da Piedade remains the most photographed section of this coast. Its rock formations — named Arco do Triunfo, Porta da Piedade, and Titanic by successive generations of fishermen — stand no more than thirty metres offshore, accessible only by water. The grottos penetrate fifteen to twenty metres into the cliff base, their ceilings open to the sky where collapse has occurred. Benagil Cave, located twenty kilometres east near Carvoeiro, draws even larger visitor numbers despite its distance from Lagos Marina. The dome-shaped interior measures roughly twenty-five metres in diameter, lit by a circular oculus that admits a shaft of daylight onto the sand floor below. Tour operators distinguish between rigid inflatable boats, which can beach inside the cave, and larger catamarans, which anchor offshore and allow passengers to swim in. Algarve boat tours from Lagos Marina operate year-round, though sea conditions govern whether captains can navigate the narrower grottos. Winter swells frequently exceed two metres, forcing itineraries to remain outside the rock arches. Morning departures between nine and eleven o'clock typically encounter lighter winds and flatter water, particularly in spring and autumn. The boats themselves range from six-passenger ribs to forty-seat sailing vessels, each licensed by the Autoridade Marítima Nacional and required to carry lifejackets in Portuguese and English. Most routes last ninety minutes to two hours, covering either the immediate Ponta da Piedade coastline or the longer eastbound run to Benagil and back. Guides narrate in multiple languages, identifying nesting sites for yellow-legged gulls and pointing out fossil layers embedded in the cliff faces. The marine reserve designation, in place since 2016, prohibits anchoring within fifty metres of the rock formations and limits the number of vessels permitted inside the larger caves at any given time.