Delaware Bay is a large estuary outlet of the Delaware River on the Northeast seaboard of the United States whose fresh water mixes for many miles with the waters of the Atlantic Ocean. It is in area. The bay is bordered by the State of New Jersey and the State of Delaware. It was the first site classified in the Western Hemisphere Shorebird Reserve Network.
The pair of Delaware Capes that denote the outermost boundary of the Bay with the Atlantic are Cape Henlopen and Cape May. The Cape May-Lewes Ferry crosses the Delaware Bay from Cape May, New Jersey to Lewes, Delaware. Management of ports along the bay is the responsibility of the Delaware River and Bay Authority.
The shores of the bay are largely composed of salt marshes and mud flats, with only small communities inhabiting the shore of the lower bay. Besides the Delaware, it is fed by numerous smaller streams. The rivers on the Delaware side include (from north to south): the Christina River, the Appoquinimink River, the Leipsic River, the Smyrna River, the St. Jones River, and the Murderkill River. Rivers on the New Jersey side include the Salem River, Cohansey River, and the Maurice River. Several of the rivers hold protected status for the unique salt marsh wetlands along the shore of the bay. The bay serves as a breeding ground for many aquatic species, including horseshoe crabs. The bay is also a prime oystering ground.
The strategic importance of the bay was noticed by the Marquis de Lafayette during the American Revolutionary War, who proposed the use of Pea Patch Island at the head of the bay for a defensive fortification to protect the important ports Philadelphia and New Castle, Delaware. Fort Delaware was later constructed on Pea Patch Island. During the American Civil War it was used as a Union prison camp.
In 1885, the United States government systematically undertook the formation of a channel wide from Philadelphia to deep water in Delaware Bay. The River and Harbor Act of 1899 provided for a channel wide from Philadelphia to the deep water of the bay. The bay today is one of the most important navigational channels in the United States, and is the second busiest waterway in the United States after the Mississippi River. Its lower course forms part of the Intracoastal Waterway. The need for direct navigation around the two capes into the ocean is circumvented by the Cape May Canal and the Lewes and Rehoboth Canal at the north and south capes respectively. The upper bay is also connected directly to the north end of Chesapeake Bay by the Chesapeake and Delaware Canal. For boaters using the bay the bay it offers several challenges. first there is a significant current which can run up to three knots giving a boost or slowing you, second - it is for the most part shallow and the channel is often occupied with ocean going vessels. When wind is in opposition to the current it builds a very nasty chop quickly. Finally it does not offer many places where you can take shelter.