Always remember to put safety first. Check the path for rocks, people and other obstacles that may be in the way. Sled at your own risk. 

Nassau:

Cedar Creek Park: Cedar Creek Park | Nassau County, NY - Official Website

Bethpage Park: https://parks.ny.gov/parks/108/details.aspx

Baldwin Harbor Park: Facilities • Baldwin Park

Eisenhower Park: Eisenhower Park | Nassau County, NY - Official Website

Suffolk:

Bald Hill: Bald Hill Ski Bowl – Farmingville Historical Society

Herman Griem Park: Hermann Griem Park - Town of Babylon Parks | Wheatley Heights NY | Facebook

South Hampton Youth Services: Home | Southampton Youth Services | Nonprofit Recreational Facility

Commack Park: Parks & Athletic Fields Directions - Town of Huntington, Long Island, New York