Yes, China has done a number on the environment. But the government is also establishing the world's largest national park. Situated on the Mongolian border, in Xinjiang province, Kanas National Park encompasses a 385-square-mile wilderness and will expand to 4,000 square miles by 2010. Go with Xinjiang Grandworld International Tours (from $1,500; grandworld-tours.net), based in the provincial capital of Ürümqi. Their five-day, 45-mile horseback trek follows the Hemu River through high grasslands and along steep mountainsides, makes an overnight stop in a Tuwa shepherd's home (go easy on the rice wine), and ends at 15-mile-long Kanas Lake. Explore the birch-forested shoreline on a four-hour hike from the lake's entrance to 6,600-foot Fish Viewing Pavilion, which is also good for ogling the Altai Mountains.
GET THERE: Fly from Beijing to Ürümqi on China Southern Airlines (from $700; csair.us).