The rabelo boat — flat-bottomed, square-sailed, built to carry port wine barrels downriver — stopped commercial service in 1964 when trucks replaced water transport. Six traditional vessels now operate passenger routes from Cais do Pinhão, the stone embankment where coopers once rolled 550-litre pipas onto decks bound for Vila Nova de Gaia. The Douro Valley earned UNESCO World Heritage designation in 2001 for its terraced viticulture, a landscape shaped by two millennia of slope cultivation. Schist terraces climb 400 metres above the waterline; quintas cling to ridges accessible only by single-track roads carved in the 1960s. Pinhão sits at the river's tightest meander, where the railway bridge — completed in 1880 with blue-and-white azulejo panels depicting harvest scenes — frames the departure point. The station's tile work, restored in 2006, shows grape treaders, barrel coopers, and ox-drawn sledges hauling fruit down vertical slopes. Departures from Pinhão access the Alto Douro's core wine country: Quinta do Bomfim, Quinta de la Rosa, and Quinta do Crasto occupy the north bank within the first three kilometres of river. The south bank rises more steeply; terraces there date to Roman settlement, with stone retaining walls rebuilt in the 18th century when Marquês de Pombal demarcated the world's first protected wine region in 1756. Modern operators run both traditional rabelo replicas and eco-solar catamarans. Solar vessels, introduced in 2019, carry 50 passengers on silent electric propulsion; photovoltaic panels generate 12 kilowatts, enough for six hours of autonomous operation. One-hour routes cover eight kilometres round-trip, passing beneath the railway viaduct and circling the São Salvador do Mundo peninsula. Extended itineraries reach Tua confluence, 12 kilometres upstream, where the tributary meets the main channel in a canyon rimmed by schist cliffs. Water depth here averages 4.5 metres year-round; five hydroelectric dams upstream regulate flow, eliminating the seasonal floods that once made navigation impossible between November and March. Audio-guided departures provide commentary in six languages, keyed to GPS waypoints. Onboard wine tastings feature estate bottles from riverfront quintas; most operators serve Quinta do Vallado or Quinta do Crasto labels. The valley's microclimate — 900 millimetres of annual rainfall, concentrated in winter — sustains 45,000 hectares of vineyard, yielding 250,000 hectolitres of port and table wine each harvest.