Yellowstone Lake has more than 13 miles of hiking trails. Trails may vary in difficulty. Steep climbs or descents and stairways may be encountered. Use caution when on steep bluffs or near a cliff. Stay well away from cliffs which are not protected by a barricade or barrier. Stay behind barricades and barriers where provided and watch small children closely. The main trail head is located at the bottom of Campground Hill Road.
From Madison: Head west on U.S. Highway 18/151 toward Dodgeville. Take the State Highway 78 South exit and head south on 78 to Blanchardville (Highway 78 will also become County Highway F). After passing through downtown Blanchardville on 78/F, turn right on County Highway F at the T-intersection where County F and Highway 78 split - there will be a road sign directing you toward the park (don't turn right at your first opportunity to take county F on the north side of Blanchardville prior to the downtown area). Continue following F for about 8 miles to Lake Road. Turn left (east) onto Lake Road (look for the large unlit park sign). The park office is about 1 mile east of County F on Lake Road on the right side.
http://www.tripleblaze.com/trail.php?c=3&i=5834