wide embayment of the Atlantic Ocean along the southwestern Iberian Peninsula, stretching about 200 miles (320 km) from Cape Saint Vincent (Portugal) to Gibraltar. At the Portuguese end—the south-facing area of the Algarve—the coastline consists of bold headlands and high cliffs interrupted by bay beaches, small river mouths, and numerous settlements. Continuing southward along the Spanish coast, the most recurrent feature is large marshes (some spreading inland as much as 30 miles 【50 km】) behind coastal dunes, which are interrupted by tidal channels, notably of the Guadiana, Tinto-Odiel, Guadalquivir, and Guadalete rivers; along this stretch are many saltworks and occasional settlements, including the city of Cádiz, on the Bay of Cádiz, which empties into the Gulf of Cádiz. Farther southward, from Cape Trafalgar to Gibraltar, rocky coasts alternate with beaches.