On a recent Sunday afternoon, the divers arrived on a thin strip of sand at the furthest, watery edge of New York City. Oxygen tanks strapped to their backs, they waded into the sea and descended into an environment far different from their usual terrestrial surroundings of concrete, traffic and trash-strewn sidewalks.
Horseshoe crabs and other crustaceans crawl on a seabed encrusted with barnacles and colonies of coral. Spiny-finned sea robin, blackfish and wayward angelfish swim in the murky ocean tinted green by sheets of algae.
