It was last winter that I visited to go snowshoeing and it turned out to be a great experience. The only problem was that it wasn't plowed up to the trailhead I went to, so it required snowshoeing for a mile or more before actually reaching the trail. However, it was a beautiful, sunny, winter day after a heavy snowfall making it perfect for snowshoeing. In some places, especially going across the field to reach the trail, the snow was above knee deep. The snow fall was so heavy that many of the trees along the trail were bent over to the ground.
You'll find shelters with fire rings at Rumble Lake, Rim Lake, and long the Indian River on the Triangle Loop. Camping is allowed anywhere throughout Pine Marten Run, but they do require a permit for camping on Swan Lake, Triangle Lake, Ironjaw Lake, and Lake Nineteen. Contact the Hiawatha National Forest Ranger District in Manistique at 906-341-5666.
You can view a map of the trail system here. There are maps at many spots throughout the trail (at least on the section I did) that indicate your location. Keep in mind that some of the loops don't have a trailhead and will require a decent number of miles to reach. At times of the year when the roads are clear you'll be able to drive in closer to different sections, but in the winter that won't be possible.
Loops (this information is taken from the US Forest Service website):
Rumble Lake - 4.3 miles long with access from FR 2258 just south of the Indian River bridge. This segment crosses through Mike White Sharptail Grouse Management Area as it traverses rolling hills of beech, birch and maple and loops around Dinner and Sprinkler Lake. Approximately one mile of this loop is
open to motorized vehicles, so users should exercise caution.
Swan Lake - 3.8 miles long with access from FR 2258 just north of the intersection with County road 440. This segment circles Swan Lake which is a popular permit camping lake. The terrain in this area is fairly level and is composed of pine plantations interspersed with hardwoods and hemlocks. Portions of this loop are also open to motorized vehicles.
Ironjaw Lake - 4.6 miles long and located in the center of the Ironjaw Area. This segment can be accessed from all the other loops except Triangle Lake. It can also be reached via FR 2733, which is the access road to the permit campsites on Ironjaw and Lake Nineteen. This loop provides scenic vistas of Verdant and Ironjaw Lakes.
Spud Lake - 6.4 miles long this loop can be accessed just north of CR 440 where it intersects with FR 2728. Traversing the central portion of the Ironjaw Semi-Primitive Area, it circles Spud Lake at the north end. This loop presents a wide variety of vegetative types, topography, plant communities and wildlife viewing opportunities.
Triangle Lake - 7.2 miles long with access from FR 437 just south of the Indian River bridge. This is the longest segment in the system. Traversing cedar swamps and hardwood ridges, approximately one mile of this segment parallels the Indian River and active beaver communities before it forks. The south fork leads to the Triangle Lake permit camping sites. The north fork leads to the interior of the Ironjaw Semi-Primitive Area and eventually completes the loop around Triangle Lake.
Directions: There are three different trailheads (2258, 440, and 437) and I've used Google Maps from Manistique to all three of them. You'll be able to change the starting point to wherever you're coming from. Click on View Larger Map under each of them to make changes to the directions. Also, keep in mind that these directions are approximate as I do not have exact GPS coordinates. They may be within a couple tenths of a mile off but will get you in the general area for each.
FR 2258 Trailhead - Toilet
View Larger Map
CR 430 Trailhead - Toilet and Drinking Water
View Larger Map
County Highway 437 Trailhead - Toilet
View Larger Map