https://www.raystown.org/things-to-do/allegrippis-trails-at-raystown-lake
A good start/end point is the Susquehannock parking lot. This allows you to park in a central location and go loop back to your vehicle at mile 16 resupply.
A few years ago the signage was very good but now the local porcupines have eaten a lot of the signs.
Starting at Susquehannock and running clockwise, I made all lefts on the well known trails in the system stopping to resupply once at my car at mile16. This is basically the "outer loop" of this trail system.
I recommend scouting this route out first before trying it in one go unless you upload my route to your watch. Start by heading east on Buck. Then take Allie, Grippis, Ridge, Ray's Revenge, Sidewinder, Osprey, Hydro Loop, Eagle, Sleek Dog, Doe and Buck back to the Susquehannock parking lot. From there take the Old Logger's Trail (blue blazes) making lefts to the Seven Points road parking lot. Cross the street and take Dark Hallow, Barrel Bay, Allegheny, Shade back on to Dark Hallow, cross he street and take Stoney Trail back to the Suquehannock parking lot.
Here is my route on Strava:
https://www.strava.com/activities/4426036370/overview
