Complex sentence: Gateway National Recreation Area contains over in total, most of it surrounded by New York City, including the Jamaica Bay Wildlife Refuge in Brooklyn and Queens, over of salt marsh, wetlands, islands, and water, including most of Jamaica Bay.
Split into simpler sentences: Gateway National Recreation Area contains over in total, most of it surrounded by New York City, including the Jamaica Bay Wildlife Refuge. In Brooklyn and Queens, the park contains over of salt marsh, wetlands, islands, and water, including most of Jamaica Bay.