Jewell Island is a small island in Casco Bay, Maine, United States. About 1 mile (1.6 km) long from SW to NE, it is located off the coast of Cliff Island. It is a state-owned island with a small but protected harbor as well as camping and walking paths. There are also WWII towers on the island. Cocktail Cove is popular for kayaking and the Punchbowl located in the north east area of the island. The island is part of the city of Portland.