Susitna 100 Course

All distances are approximate. Some are rounded up, some are rounded down. The total distance is very close to 100 miles.

General Description

the course photoThe current 100-mile course has evolved through changes in availability of checkpoint locations. Attached to this document is a link to a map that depicts the Susitna 100 course. The rivers and lakes that are named in this description can be oriented to the U.S. Geological Survey's Tyonek Quadrangle, should the truly curious want a clearer picture of what the course looks like in, say, mid-July. In February, however, this country is reduced to two colors, white and green, and is typically framed by a blue sky. Thanks to drifting snow, the region's shallow topography is barely distinguishable. This classic rendering of winter in simple colors and contours is marred only the intrusion of four-foot wide snow machine trails that run for miles across lakes and rivers and through breaks in the tree line. You are grateful for these trails, because they provide the foundation that makes human-powered travel faster than would otherwise be possible.

See Su 100 Maps


The Susitna 100 starts at 9:00AM Saturday.

All Susitna 100 racers are required to check in at least 15 minutes before the start and declare a division. If some of your equipment did not pass inspection at the pre-race meeting, it will be checked after the 9:00AM start.

The race starts (and finishes) at Happy Trails Kennels mile 4.5 West Lakes Blvd, Big Lake Alaska. Allow two hours driving time from Anchorage.

Driving directions from Anchorage –

North on Hwy 1 (Glenn Highway), Hwy 1 turns into Hwy 3 (Parks Highway), go through Wasilla, turn left on Big Lake road at mile 52. Drive 3 ¼ miles on Big Lake Road, turn right on Beaver Lake Road, go 1 mile, turn left onto West Lakes Boulevard (long name, short sign "W.Lks.Blvd"). Approximately 4 ½ miles turn right at sign for Happy Trails Kennels.


After leaving the start at HTK and passing the lower parking lot, you will go through a set of trees and then turn right.  The trail follows a series of swamps crossing Big Lake Trails #3 and 4.  Approximately 5 miles in, you will cross the Little Su River continuing on up the Cliff trail. Take the first left onto the 'Bud Smith' trail heading south. This section crosses the Little Su again undulating over the next 5-6 miles to the four corners intersection.

Heading straight ahead through this intersection the trail continues a couple more miles turning left for a short section then right again leading to the Little Su boat Launch. Across the Little Su and follow the boat launch road to the intersection with Ayrshire Road.

Follow along Ayrshire Rd staying on the left shoulder to the parking lot approximately 100 yards from the intersection.

Do not travel on the road! We do not have permits or insurance that allows travel on the road. You will be disqualified if you run, ride, or ski on the road!

If you race isn't going as planned at this point, this would be a good place to consider your options as this is the last road access point for many more miles!


After leaving The Ayrshire Rd parking lot you will cross the Boat Launch road heading straight ahead, the trail more or less becomes a continuation of Ayrshire Road, for about 5 miles, the trail then bears right onto seismic line headed west.

Approximately 5 more miles the trail enters the woods just prior to Flathorn Lake. A steep decent followed by a right hand turn leads you to the lake where the trail will take you to the far bank. Take care to stay off of the marked runways in this area. About ¼ mile up the shoreline you will find the Flat Horn Lake checkpoint in the red cabin beyond the silver house. This property is home of long-time race supporters Kirk and Peggy Garoutte. Please respect their property and relieve yourself only in the outhouse.


Leaving the checkpoint, the course continues along Flat Horn Lake in a northwesterly direction. Two miles later, at the north end of the lake, the course parallels a meandering inlet creek. Follow the trail markers and stay off of the creek. After about 1/2 mile of travel through the woods, the trail opens up onto "The Dismal Swamp."

The Dismal Swamp is about 3 miles long and is appropriately named. Only the occasional scrawny black spruce tree belies the impression that you are on a lake. With the wind blowing hard from the North, as is tradition, this can be a brutal and disheartening section. Otherwise, the three miles is simply boring.

At the north end of the swamp, the trail takes you out of the wind and back into the forest for about 1.5 miles to the main Susitna River. Descend the steep drop – "Wall of Death"- onto the main channel of the Susitna River (locally called the Big Su).

WALL OF DEATH TO 5-Star Checkpoint

Once you are on the Susitna River, head to the right (upstream). There will be many snowmobile trails here, so pay close attention to the Su 100 markers. About a mile upstream, you will come to a major intersection, the course turns right towards the riverbank/woods. After accending a steep hill you will be on the Willow Swamp trail. After about 2 miles the trail will split, stay left towards Willow following the race trail markers. Look for the checkpoint on the right of the trail in about 5 miles.

Advice on Traveling the Rivers-

The Rivers are a main transportation route to Skwentna and Yentna Station, as well as numerous cabins and fishing lodges. The trail is usually very firm due to high volumes of traffic. Expect snow machine and dogsled traffic..

At night, you will generally be alone except for other racers and race support. You are strongly discouraged from sleeping on the Susitna Rivers. Not only is it much colder than other sections of the trail, but snow machines travel very fast along these rivers and may not see you. Keep a close eye for race markers.


After 5-6 more miles of swamp travel, depending on conditions, the trail will eiither continue straight to the Willow Swamp loop or turn right onto the Old Hunter Trail. Both trail lead to the Eaglequest Checkpoint and are similar distance. As always, pay close attention to the trail markers.


After leaving the comfort of Eaglequest Lodge you will return to the Willow Swamp Loop turning left, following the loop clockwise. Take a left onto a trail leading to North Rolly Lake. After crossing North Rolly lake you will cross the Nancy Lake Parkway rd (closed in the winter), and travel through the S. Rolly Lake Campground before dropping onto South Rolly Lake.The trail continues on to Redshirt lake. You will travel the length of Redshirt lake and across the 1 mile portage to Cow Lake. Once on Cow lake, the trail takes a hard right turn to the Cow lake Checkpoint 100 yards down the shore.


At the far end of Cow Lake the trail goes over a small hill to Little Cow Lake. Bearing left at the end of the lake you'll take the Cow trail #10 towards Butterfly Lake and Gunmetal Lake eventually turning into Trail #4. After about 9 miles you will travel under the intertie (overhead power line) for about a mile or so and crossing the Little Susitna River. The race trail turns right again, shortly after which you will come to the Big Hunter Loop Tent/Water stop. After leaving the water stop the trail meanders through a big swamp following the Little-Su River to your right, eventually turning left onto a seismic line briefly before turning left again following more swamps and small lake eventually leading to Happy Trails Kennel.

Congratulations, you've made it!

Be sure to check in with the race official!