This is a multi-cache with a puzzle/activity needed to be solved in the middle to keep going. The puzzle/activity are in a Civil War encampment display set up in the Visitor Center. Most caches can be found along the river's edge or overlooks.
Each multi-cache you will find has an interesting story about the supply train of McClellan's army. If you can't figure out the coordinates during the puzzle/activity portion of the cache, find a Ranger for the answer. The final cache is not on a designated trail, so keep an eye on the river.
Gur chmmyr/npgvivgl pyhr gb pbbeqvangrf vf: A 37 24.844 J 76 42.644Gur svany pnpur vf ba n aba-qrfvtangrq genvy; yrsg fvqr orsber Znggncbav Genvy va n yrna-gb.