Cruise lines that operate South American ocean cruises include Fred Olsen and P&O Cruises. Due to South America being in the southern hemisphere, and therefore their seasons being the opposite of ours, the best time to visit South America would typically be from November to early May, and this is when most cruise lines run their journeys there. Always, be prepared for a variation in climates that can change hourly to daily.
South America voyages from Southampton tend to be longer cruises of sixty nights or more, and will usually travel around the South American continent, visiting many of the South American countries along the way including Brazil, Uruguay, Argentina, Chile, Peru and more, going round the "horn". The journey "around the horn" usually involves many of the fjords, and the beautiful wilderness of Patagonia and Cape Horn, which is the southernmost point of South America. The "horn," of course, is the infamous Cape Horn, which is the closest most people will ever get to Antarctica, which lies approximately a thousand miles further south.
The greatest feature of this itinerary is the Chilean fjords, whose splendour surpasses even those of Alaska; and Patagonia which is a land of deserts and mountains that stretch between Argentina and Chile. There are relatively few ports visited on these itineraries simply because the region and journey are so huge, although you can expect in the region of 25-30 ports over a 65 night voyage. Some ships will also include stops at Stanley in the Falkland Islands.
These longer cruises will then continue up the Pacific coast of South America, and then cross through the Panama Canal to visit the Caribbean islands including Barbados, St Lucia, Guadeloupe, St Maarten and Bermuda before returning to Southampton via Ponta Delgada in the Azores.
South America is a continent one cannot rush around. Instead it should be taken at leisure. Whichever itinerary or length of trip you choose, you can be sure that a visit to South America will be something you will remember for the rest of your days.