Searsport is an incorporated town and deep water seaport located at the confluence of the Penobscot River estuary and the Penobscot Bay immediately SE of Sears Island and Cape Jellison in Waldo County, Maine, United States. Where the freshwater mixes with ocean tides, the River becomes an estuary and serves as a spawning and nesting area for fish, shellfish and birds.

Bucksport is a historic town in Hancock County, Maine, United States.The population was 4,924 at the 2010 census.Bucksport is across the Penobscot River estuary from Fort Knox and the Penobscot Narrows Bridge, which replaced the Waldo–Hancock Bridge Searsport includes the village of North Searsport.

The town is known as "the home of the famous sea captains" and the "Antique Capital … A hydrographic survey of the Penobscot River (Maine) estuary, made during 1963–65, showed that the lower estuary is subject to a high degree of stratification, extensive mixing occurs within intermediate strata in the middle reaches of the estuary, and near-uniform conditions prevail at the head of the estuary. The Penobscot is also a significant freshwater inflow to the Gulf of Maine, discharging 10 billion gallons per day (Hasbrouck, 1995). Searsport is an incorporated town and deep water seaport located at the confluence of the Penobscot River estuary and the Penobscot Bay immediately SE of Sears Island and Cape Jellison in Waldo County, Maine, United States. Tidal marshes are both important sites of in situ methylmercury production and can be landscape sources … The transport and trapping of this contaminant is linked to the transport and trapping of fine sediment within the estuary. The transport and trapping of this contaminant is linked to the transport and trapping of fine sediment within the estuary. The Penobscot River Estuary is heavily contaminated with mercury; previous studies indicate maximum mercury concentrations of 4.6 ppm within the Frankfort Flats reach. the Penobscot estuary, especially in some wetlands, is more efficient than at most other studied locations. "The Penobscot River estuary is a complicated, complex system, difficult to monitor, and there is much to know about its function and role in fish production," said O’Malley, a fisheries scientist at the Orono Field Station, which is jointly supported by NOAA’s Northeast … The Penobscot River Estuary is an important system for diadromous fish in the Northeast United States of American (USA), in part because it is home to the largest remnant population of Atlantic salmon, Salmo salar, in the country. Islands and rocky shores dominate, but in the upper reaches, along the Marsh River in Frankfort and the Orland River, are extensive salt marshes and mudflats where the current slows down enough for sediment to settle out from the water at high tide. Little is known about the chemical and biological characteristics of seston in the Penobscot River Estuary. Electronic address: dkopec@maine.edu.