Three different forts on this New York City island, part of harbor defenses including the star fort base of the Statue of Liberty (above left), were built just before the war of 1812, so the British didn’t invade the city again. Great.
But the amazing part is the rest of the island, which is both extremely close to and completely different from the city. The view above from a replanted woody hill extends around the whole harbor. While many military buildings are still empty waiting for renovations and more ideas, most public spaces are wonderful. There are hammocks, Adirondack chairs, picnic tables, grills, bike rentals, a day spa with pools facing the skyline, an excellent Neapolitan pizza place, a cafe, a patio bar, an oyster bar, and a taco truck with unimpeded views of the Brooklyn Bridge. And there are lots of birds! And an oyster shell recycling operation that builds new oyster beds, and a solar powered plastic recycling 3D printing enterprise. And there’s space and art and no crowds and the ferry only costs $4. Perfect side trip while passing through Manhattan!
Zero Carbon Travel 
I’ve sailed right by Governors Island and never realized it was so interesting. Can one visit the island on one’s own boat?
No private motorized boats allowed. There’s a kayak dock on the east side, so I briefly considered kayaking from Brooklyn to avoid taking the ferry. But they’re set up to rent kayaks there on weekends, not accept visitors nor store my kayak while I walk around.
Thank you.