Trail 91 (Mud Lake Trail) is part of the Mineral Point Trail System located in the Kaniksu National Forest. It is a very quiet, peaceful trail predominately consisting of hard packed dirt base that take you on a small journey through a dark forest. Damp trail conditions are common on the trail. Be on the lookout for moose and other wildlife.
Starting from the south trailhead off of Green Bay Road, the trail climbs abruptly and then quickly levels out and then gently descends to Mud Lake through the forest. As you are approaching Mud Lake, the trail does a right switchback leading you down along the west and around the southern end of the lake.
There are some benches that overlook the lake to relax on and take in the quiet surrounding area. The trail continues along the eastern shore of the Mud Lake and then back into the woods and alongside a small, marshy area and then ends at the north trailhead as it T's into Lost Lake Trail 81