Chebeague Island is an island town in Cumberland County, Maine, United States, located in Casco Bay, 10 miles (16 km) from Portland. These islands are sometimes referred to as an older, now archaic term "The Calendar Islands" because there was once a belief that the approximate number of islands was 365. The actual number is fewer than two hundred. Great Chebeague was a part of the town of Cumberland until July 1, 2007, when it became the town of Chebeague Island.