Of 16 counties in the Vacationland, Penobscot County ranks fourth in terms of size (3,557 square miles). Penobscot County is in Northwest Maine. The total value of approximately 1,000 acres of riverfront homes and property recently listed for sale in Penobscot County, Maine, was nearly $100,000. Browse all waterfront property for sale in Penobscot County on the Land Network to find the marina, lakefront and other recreational property that meets your needs, from waterside land perfect as a retirement investment to existing residential waterfront land and property for hunting, fishing and other outdoor-recreation pursuits! The most common type of land for sale by combined acreage in Penobscot County is house.