It is bordered to the west by Penobscot Bay, to the south by Castine Harbor and the tidal Bagaduce River, to the northeast by Hatch Cove, and to the northwest by Wadsworth Cove, an arm of Penobscot Bay.

The CDP crosses the "British Canal", a small waterway cutting the isthmus and connecting the two coves, and extends north as far as Shore Road.

[3] Maine State Route 166 has its southern terminus in Castine, and leads north 7 miles (11 km) to West Penobscot.

Bucksport is 17 miles (27 km) north of Castine via Routes 166, 175, and 1.

[2] The Maine Maritime Academy is located in the Castine CDP.