Its area is 550 acres (2.2 km2) and has a rocky shoreline with open fields and softwood forest dotted by ponds, residential properties and fish stores.

It is separated from nearby Little Tancook Island to the east by a 1 km (0.6 mi) wide strait called "The Chops".

Wildlife populations are limited to deer, muskrats, snakes, and pheasants, and a great variety of birds.

The word "Tancook" is an anglicized Mi'kmaq term that translates into "facing the open sea."

The MV William G. Ernst is a passenger-only ferry operated by the provincial Department of Transportation and Infrastructure Renewal.