New York City is a stopover for many migratory birds. This area, with it's marshes and shoreline has long been held in trust for the benefit of the birds who have use it. It was included in the National Park system (Part of Gateway Natl Pk) and opened to the public to allow them to walk the marsh trails and view birds in their natural habitat.
I've been going here for a long time, and always try to find time to marvel at this piece of Nature preserved in the massive sprawl that is New York City. It is a great day outdoors in a natural surrounding, the kids can run and have a good time while learning about their environment and it's natural balance.
A great learning center, well worth the trip. There is parking but it can get crowded on the weekends.