Well, take 95 south into Mass, to 495 to the end, which is pretty much Cape Cod. As soon as you cross the Bourne Bridge in Bourne, Cape Cod, you come to a rotary. If you go straight through the rotary, you'll see sand trails off to your left. If you go pass them, when you get to the second rotary(the Mass. Military Reservation) you'll see another set of trails if you go 3/4 around the rotary. Most of the trails are off the base, you'll know if you've traveled on because of signs. A friend of mine told me they're old Humvee training trails, but are no longer used. So they have a little of everything. As far as permission to ride, I've never had a problem driving the trails, but I've never investigated if it is totally permitted. I hope this helps out some.