According to the United States Census Bureau, the town has a total area of , of which is land and , or 45.68%, is water. It is bordered by Cape Cod Bay and the Atlantic Ocean on its western and eastern sides, respectively. Eastham is also bordered by the towns of Wellfleet and Orleans on its northern and southern sides, respectively. Eastham is located on the "forearm" of Cape Cod, and is south of Provincetown, the same distance east-northeast of Barnstable, east of the Sagamore Bridge, and (by land) southeast of Boston. Approximately one-third of the town is located within the Cape Cod National Seashore. There are several freshwater ponds near the center of town, the largest being called Great Pond, which has two public beaches. Powerboats with 50 and under horsepower motors are allowed on Great Pond and Herring Pond, with water skiing only permitted at Great Pond on even numbered days. Along the Atlantic coast, portions of the CCNS include several islands, divided by channels which lead from Nauset Bay and Salt Pond Bay to the ocean. The town also shares Town Cove with neighboring Orleans. Several creeks and the Herring River run inland from the bay side. The town of Eastham has a mild summer Humid continental climate (Dfb). The plant hardiness zone is 7a with an average annual extreme minimum air temperature of 4.1 °F (-15.5 °C). The average seasonal (Nov-Apr) snowfall total is around 30 in (76 cm). The average snowiest month is February which corresponds to the annual peak in nor'easter activity. U.S. Route 6 passes from south to north through the town. The Cape Cod Rail Trail, as well as several other bicycle routes, pass through the town. There is no rail or air service in town; the nearest regional air service is at the Chatham Municipal Airport, though better and more regularly scheduled air service between the Cape and Boston can be found in Provincetown and Hyannis through Cape Air, and the nearest national and international air service can be found at Logan International Airport in Boston. Eastham is also served by an inexpensive regional bus service, The Flex. As of the census of 2010, there were 4,956 people, 2,396 households, and 1,634 families residing in the town. The population density was 389.8 people per square mile (150.5/km2).