Poás Volcano National Park, Costa Rica

The main crater of this active volcano is one of the largest in the world, and it's definitely worth a hike to the rim. While getting to Costa Rica takes a pricey plane ticket, food is inexpensive and public transportation plentiful.

A budget of $45 to $80 a day can accommodate thrifty travelers. Visit during the cheaper rainy season from May to November if getting wet isn't a deterrent.