Multinational programs include:
Ecovolunteer Nature Travel offers ecotourism to North and South America, Europe, Asia, and Africa.
Sea Shepherd offers pirate-style conservation for volunteers.
Willing Workers on Organic Farms offer farmstays around the world.
Worldwide Veterinary Service takes vets, vet students, vet nurses, and non-vets to a variety of countries around the world to give out veterinary care.