You will be looking for a camouflaged bison tube.
Pisgah Reservoir is the largest body of water, at 120 acres, in Pisgah State Park. To get here from the closest parking requires a 3/4 mile uphill walk, in summer, as long as the Reservoir Road gate is open. The gate usually opens Memorial Day weekend and closes after hunting season. This cache is winter friendly, if one is up for a long, winter-time walk.