Islesboro
is the marker for dividing East Penobscot Bay from West Penobscot Bay. It includes North and South Islesboro connected by a narrow segment of land, See chart and photo. Seven Hundred Acre Island, Job Island. The 129 acres of forested Warren Island hosts a state park with a dock and moorings. Grindel Point Light Station in Gilkey Harbor on Islesboro was established in 1850.