Mark Twain National Forest is a U.S. National Forest, located in the southern half of Missouri. The MTNF covers 3,068,800 acres. Features of the Mark Twain include Greer Spring, which is the largest spring on National Forest land and part of the Eleven Point National Scenic River. The public can also visit the Glade Top Trail National Scenic Byway, which offers views of over 30 miles to the Boston Mountains. The 350-mile Ozark Trail system winds through much of the National Forest.