Searching for a destination that's not mobbed by river cruisers? Head to Andalusia in southern Spain — the land of flamenco, tapas, and matadors — along the Guadalquivir River. Only one major line, CroisiEurope, offers sailings here, with itineraries that typically depart from Seville, cross the Gulf of Cádiz, and ascend the Guadiana River along the Spain-Portugal border. Excursions to Córdoba and Granada leave from Seville, and some cruises also offer extensions to Gibraltar.
Voyages are available late April through November, but if you book during the summer months, expect some fierce heat and sun.