Big Tancook Island is a Canadian island located off the coast of Nova Scotia. The island is one of the 365 islands dotting Mahone Bay. It measures approximately 4 km (2.5 mi) long (north to south) and 1.6 km (0.99 mi) wide, forming roughly a "C" shape. The island is separated from nearby Little Tancook Island to the east by a 1 km (0.62 mi) wide strait called "The Chops".