Are you adventurous? Try this cruise in Chile (I did it 10 years ago):
http://www.navimag.com/navimag/html/ingles.htm
Every year, tourists from all over the world live the unforgettable experience of getting to know the mythical, scarcely explored lands of Patagonia.
The ideal setting for an adventure, Patagonia is a natural region with landscapes ranging from the pampas to the fjords and channels in which the snow-covered peaks of the Andes Cordillera are submerged. In this place, vast extensions of temperate rain forests merge with the multicoloured waters whose glaciers tell of the continental ice fields, mute witnesses of the latest glaciation.
On ferry-type vessels, Navimag offers the most extensive coverage in navigable routes through Patagonia, welcoming tourists and residents who are willing to be dazzled by its wild nature and to enjoy the experience of sailing through the channels bound for Puerto Montt, Chiloé, Puerto Chacabuco, Laguna San Rafael and Puerto Natales.
The cruise is cheap, but flying to Santiago can be expensive. Consider also a crusie to the Galapagos. For my honeymoon we took ferrys around to the Greek Islands. That is relatively inexpensive and lots of fun. One of the ferrys we took hit a reef and sank a few weeks later because the entire crew was watching a soccer game, and no one was steering the ship.