Eastham is a town in Barnstable County, Massachusetts, United States, Barnstable County being coextensive with Cape Cod. The population was 4,956 at the 2010 census.
Today, Eastham is mostly known as the "Gate" to the Cape Cod National Seashore, which was founded in 1961 by President John F. Kennedy to protect Cape Cod's coast from erosion and overpopulation. The town is the site of many beaches, both on the Atlantic and bay sides, as well as the Nauset Light, which was moved to the town in 1923 from its old location in Chatham, and the Three Sisters Lighthouses, which have since been moved away from their now-eroded perches on the coast to a field just west of Nauset Light.
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.