Secrets of the Blue Zones

The first blue zone on the list is Costa Rica's Nicoya Peninsula, a small region located about a two-hour trip on bumpy roads from the national capital of San Jose. Nicoya is the biggest blue zone on earth—home to literally hundreds of centenarians.

To see what makes the residents of the Nicoya Peninsula so vital, Dr. Oz and Dan paid a visit. There, they met 102-year-old Panchita, who still chops wood every day for cooking; 86-year-old Filippa, who sells her homemade tamales; and 95-year-old Serillo, who was cruising by on his bike as he visited with neighbors.

But to meet one of the oldest Nicoyans, Dan took Dr. Oz on a hike deep into the rainforest.