This annual fest celebrates the natural resources of the New York harbor with a host of aquatic-based highlights. Sail to Governors Island or Maxwell Place Park in Hoboken for a kids' fair featuring ecology-themed games and activities. Families can also get gratis access to a plethora of watergoing vessels, including canoes, kayaks and rowboats; or fish, bike or kick back with food and music on dry land. Check cityofwaterday.org for events taking place throughout the five boroughs. All ages.