Known for its white sand beaches and insane sea-life diversity (think massive whale sharks and 1000-pound leatherback turtles), Malaysian Borneo and its surrounding waters are already a dream vacation. But the non-profit Tropical Research and Conservation Centre offers travelers an opportunity to do more than simply sit on the beach. TRACC hosts week-long courses in things like marine biology and coral reef ecology coupled with field work, including the chance to replant coral reef in places where bomb fishing has annihilated it. Not only will you be beautifying the ocean, but you'll also be helping to preserve the local aquatic ecosystem in the process.
You Need: A diving certificate, or a few extra days to earn your C-card on-site. ($1280 & up; govoluntouring.com)