Custer State Park is known for its free-ranging bison herd. With some 1,500 animals, it is one of the largest bison herds in the world. Pronghorn, deer, elk, mountain goats, bighorn sheep, mountain lions, burros, prairie dogs, coyotes, eagles, and wild turkeys are other residents of the park’s variety of habitats. The 18-mile (29-km) Wildlife Loop Road offers views of the animals, and bison often stop traffic as they cross. The Needles Highway is a twisting 14-mile (23-km) route through narrow tunnels and past needlelike rock formations, including the Needles Eye, a granite spire some 30 to 40 feet (9 to 12 metres) high with a small slit 3 to 4 feet (0.9 to 1.2 metres) wide. The park offers hiking, biking, rock climbing, and horseback riding and has several resorts.