The Town of Smithtown is located at 40° 52' 13" North, 73° 13' 3" West (40.862786, -73.215175) [REF].
According to the United States Census Bureau, the town has a total area of 111.4 square miles (288.5 km²), of which, 53.6 square miles (138.8 km²) of it is land and 57.8 square miles (149.7 km²) of it (51.89%) is water.