Until the winter of 2007 the two islands were connected by a narrow two-mile (3 km) strip of beach (Katama Beach), which from time to time would become breached due to weather. As of April 2007, the two entities are not connected, separated by a breach caused by a strong storm. The southeastern point of this beach is called Wasque Point—a popular fishing point to catch bluefish, striped bass, etc.
A privately owned barge-like ferry called the On Time shuttles walk-on passengers, bicycles and up to three cars at a time between Chappaquiddick and downtown Edgartown, on Martha's Vineyard. Two ferries run during the summer, and one during the off-season.
Chappaquiddick Island comes from an Indian word "cheppiaquidne" meaning "separated island"; so named because this island is separated from Martha's Vineyard by a narrow strait
Historically spelled as "Chaubaqueduck" or alternately spelled "Chappaquidgick"
Once mainly the home territory of the Chappaquiddick Band of Wampanoag Indians remaining theirs even into the early 1800s it still has a reservation of about a hundred acres of brush land on the interior.
On a map, Chappaquiddick can be located at . The United States Census Bureau defines it as Block Group 1, Census Tract 2003 of Dukes County, Massachusetts. It has 15.915 km² (6.145 sq mi) of land.
Politically, it is part of the town of Edgartown in Dukes County. Socially, its residents form a tight-knit community and see themselves as distinctly separate from the rest of Edgartown. Longtime residents speak of "going to the mainland" when they travel to Edgartown and of "going to America" when (for example) they travel to Boston or Cape Cod. As of the 2000 census the island had only 172 year-round residents and 475 houses, as well as numerous wildlife preserves and beaches. It has just one combination general store/automobile mechanic's garage, which is only open in the summer.