Hoffman Island: Park, Staten Island, NYC

Completed in the early 1870s, the island originally isolated ship passengers suspected of contagious diseases, while those confirmed sick went to neighboring Swinburne. During World War II, it served as a Merchant Marine training center and an operations post to control defensive harbor mines. Now part of Gateway National Park, the site is strictly off-limits to humans. The only way to experience it is from the water, often as a scenic marker when you pass by kayak on the way to spot Swinburne's winter harbor seal colony.