South America offers the best of two worlds: the natural one, in the Amazon, Galapagos, and the northern reaches of Antarctica; and the urban one, from beautiful Buenos Aires to Rio de Janeiro, Caracas, and Montevideo. Itineraries range from seven days to several weeks and often cruise between Rio or Buenos Aires and Valparaiso, Chile (relatively close to Santiago). Cruises that focus on the Amazon River typically sail between Manaus, Brazil, and Rio or Buenos Aires. If you’ve got the time, see it all with a cruise circumnavigating the continent.