Greenbelt Trail is a hiking, biking, and horse trail in Smithtown, New York. It is within Blydenburgh County Park, Suffolk County Park, Caleb Smith State Park, and Sweetbriar Park. It is 4.9 miles long and begins at 36 feet altitude. Traveling the entire trail is 4.2 miles with a total elevation gain of 308 feet. Along the trail there are a wetland and a parking.