About 4 miles from Golconda as the Crow Flies, an hour and a half by road. 55 minutes from the ferry is Mantle Rock Preserve. The arch is 188 ft. long and 30 ft high! The trail to it is nice and a nice parking lot. There is also a creek running under it, and it is FANTASTIC to hike along and through. There are long passages along it that go under rocks that are high enough to stand or crouch a long way. I liked it as much as the arch and you wouldn’t know it was there without getting a little adventurous.
There is also a must see waterfall (Joy Falls\ Mandy Falls same falls) very undercut where you can go behind it along the road there, just keep looking to the right on the way. I don’t think there are any signs along the road about it, but it is part of the preserve too!
We had a great day there.