A UNESCO World Heritage Site, beautiful Blue Mountains National Park lies 81 km west of Sydney and is a popular day trip from the city. Named for the blue haze emanating from the many eucalyptus trees, this stunning park protects more than 664,000 acres of bush land and encompasses dramatic gorges, waterfalls, aboriginal rock paintings, and 140 km of hiking trails. The most famous attractions in the park are the towering sandstone rock formations called the Three Sisters. Other highlights include the Katoomba Scenic Railway, the world’s steepest, which whisks passengers down the Jamison Valley through a cliff side tunnel into an ancient rainforest. Hiking, abseiling, rock climbing, mountain biking, and horseback riding are all popular things to do in the park.