The Detroit Zoological Society (DZS) is a nonprofit organization that operates the Detroit Zoo in Royal Oak, Mich. and the Belle Isle Nature Center, located in Detroit. Accredited by the Association of Zoos & Aquariums, DZS employs approximately 350 full and part-time employees and hosts more than 500 volunteers throughout the year. The 125-acre Detroit Zoo is a natural habitat for more than 2,000 animals. Major exhibits include the National Amphibian Conservation Center, Polk Penguin Conservation Center, Deveraux Tiger Forest, Great Apes of Harambee and Arctic Ring of Life, voted the number-two zoo exhibit in the U.S. by the Intrepid Traveler's guide to "America's Best Zoos". The Belle Isle Nature Center, nestled on 6 acres of Michigan's forested wetland on the northeastern tip of Belle Isle State Park, offers guests unique educational, environmental and natural experiences that help connect them with urban nature. Admission to the Belle Isle Nature Center is free of charge.