Travelers cage-dive in the Indian Ocean and collect data on Great White sharks. A dangerous water predator, the Great White is also a member of a threatened species. With the instruction of scientists, a dive master, and other trained shark professionals, volunteers can help track and record shark activity to monitor breeding patterns. No need to run out and get SCUBA-certified: Great Whites are surface feeders, so a snorkel is enough. For those who are too afraid to jump into the water, the views from the boat are just as impressive.
Trip Tip: Make sure to spend an afternoon on the cliffs at De Kelders in Gansbaai, for some of the best land-based whale-watching in South Africa.
Luxury Level: Travelers stay in a lovely red brick house with views of the harbor. Lodging rooms have semiprivate bathrooms, a shared kitchen-and-living area.

Key Wildlife and Environmental Conservation: Enkosini Eco Experience; 206/604-2664; 27-82/265-5955;; from $1,395 per person for two weeks; year-round.