Mouth of Douro

The Douro reaches the Atlantic at Porto after crossing northern Iberia from the mountains of Castile. Its estuary opens the river valley to the sea, with Porto on one bank and Vila Nova de Gaia on the other. Wine from the steep vineyards farther upstream was carried downriver in flat-bottomed boats known as rabelos and stored in Gaia's cellars. The river mouth thus joined the inland wine country to the maritime trade for which Porto became known.