The Long Pond Trail is located south of Otter Cliffs on the way to Southeast Harbor. There is some parking there, but if it is full (and that's pretty likely) continue south maybe a quarter mile and theres a wide area on the right where you can park. You could walk back on the road, but I believe it connects directly to a path down to the trail. The trail is something over 3 miles total and is all on private land. No bikes are allowed on this section. I like to go clockwise to reach the bridge, which is the only bridge in the park made with Cobblestones. You continue to the right after the bridge, or you can go down along the stream and walk a really neat trail through the woods and over some makeshift bridges for maybe a half mile or more through the woods coming out at a field close to the pond. There's a boathouse on the pond and there used to be a boat in it, but not this year. I've been told that if you see a really pristine carriage on this trail it is one of the Rockefellers (although they may or may not be in it).