Northfield encompasses 28.6 square miles of land area and 0.3 square miles of inland water way. The Winnipesaukee River forms most of the town’s north border while the Merrimack River forms part of the town’s west border and the Tioga River forms a portion of the east border. The land is characterized by gently rolling hills which are mostly forested at this point. Knowles Pond on the east side of town and Sandogardy Pond in Northfield’s southwest corner are the largest water bodies in town. Williams Brook flows through the center of town, starting at Knowles Pond and continuing north to the Winnipesaukee River.