Parking: Alongside Hurricane Mt. Rd, before the gate, near the water tower. Look at the coordinates for The Gate GC68Z3D which is not far beyond the area to park.
The Loop: A Great Winter Hike: Walk up Hurricane Mt. Road to the parking for the Black Cap Trail (at the height of land). Take the trail towards Black Cap, stopping to study the map at the kiosk along the way. At the first intersection, take the Cranmore Trail (right) just 0.2 mile to the Red Tail Trail (on right). This trail is for bikes and foot travel and has many switchbacks. You will have stupendous views of Kearsarge, Mt. Washington, all of Crawford Notch and the Moats. When you have zigzagged through the clearcut with the views, you will turn briefly into the woods and get near GZ.
The Cache: is located about 50 feet off of the trail. It is not really winter friendly, but you might be able to access it if there is less than a foot and a half of snow and maybe even deeper if you can spot part of the clue and dig down.
On The Way Down: you will pass through lovely hemlock forests (and there is a cache by that name about half way down. There will be one more viewpoint, although not as far-seeing. And best of all, the lower part of the trail follows a scenic brook. You will come out at a large water tank...head to the left of it, then turn right and you might see your car.
There is still room for more caches along this trail. It can be hiked in the other direction. And, you can include the summit of Black Cap which is 0.4 mile further out on the Black Cap Trail.
A map of the Green Hills Preserve of the Nature Conservancy can be found here: http://www.nature.org/ourinitiatives/regions/northamerica/unitedstates/newhampshire/places-preserves/green-hills-map-guide-for-web.pdf