The Murderkill River is a river flowing to Delaware Bay in central Delaware in the United States. It is approximately 21.7 miles (34.9 km) long and drains an area of 106 square miles (270 km2) on the Atlantic Coastal Plain.

Delaware Bay is the estuary outlet of the Delaware River on the northeast seaboard of the United States, lying between the states of Delaware and New Jersey. It is approximately 782 square miles (2,030 km2) in area, the bay's freshwater mixes for many miles with the saltwater of the Atlantic Ocean.