The Guadalquivir is the only navigable river in Spain, a 657-kilometre artery that carried Roman grain barges, Moorish trade galleys, and the caravels of Magellan and Elcano before they circled the globe in 1519. Seville boat trips today follow the same five-kilometre urban corridor those explorers knew, though the riverbanks have been reshaped by centuries of silting, flood control, and the dredging campaigns that kept the port alive until containerization moved shipping to Cádiz in the 1970s. The water itself runs tidal and brackish this far inland, its level rising and falling with the Atlantic's push 90 kilometres downstream. The river tour route threads between two distinct Sevilles: the eastern bank holds the Torre del Oro, a dodecagonal Almohad watchtower built in 1220 to anchor a chain-and-pontoon barrier across the current, and the bullring at La Maestranza, whose whitewashed arches have faced the water since 1761. The western bank belongs to Triana, the working-class quarter that supplied Seville's ceramic tiles, flamenco singers, and half its bullfighters. The Isabel II bridge, an 1852 iron truss span locally called the Puente de Triana, was the first fixed crossing here and remains the visual hinge of every Guadalquivir river cruise. Most Seville boat trips tours depart from the Muelle de la Sal or Torre del Oro quays, running north past the Cartuja monastery island—site of Expo '92, whose skeletal pavilions still punctuate the left bank—then returning south beneath six bridges, the oldest stone, the newest cable-stayed glass. Evening departures time their return to catch the cathedral and Giralda tower backlit at dusk, when the river turns copper and the city's profile compresses into a single jagged silhouette. Eco-certified vessels now dominate the fleet, their electric or hybrid engines required under municipal noise ordinances enacted in 2021 to protect the riverbed's migratory fish corridors. The Guadalquivir no longer carries commerce, but it remains the city's geometric and symbolic centre, the surface that taught Seville to look outward.