Lovely quiet retreat near Prospect Park is more intimate than the Bronx Botanic Garden & is near other attractions: Brooklyn Museum, Grand Army Plaza, etc.
Small aquarium by the sea. Great exhibits, some hands-on. Wonderful for kids. Afterwards, the beach and the boardwalk await.
Take a walk on the edge in DUMBO. You won't believe how close you can get to the river. Then explore the surrounding nabe's galleries & eateries.
Forget the hubbub of the city; be still and be one with nature here in this marshy expanse.
Forget the Circle Line: go fishing or on a sightseeing or dinner cruise on one of the boats at Sheepshead Bay. Lots of good eating in the neighborhood, too.