Lewes is an incorporated city on the Delaware Bay in eastern Sussex County, Delaware, United States. According to the 2020 census, its population was 3,303. Along with neighboring Rehoboth Beach, Lewes is one of the principal cities of Delaware's rapidly growing Cape Region. The city lies within the Salisbury, Maryland–Delaware Metropolitan Statistical Area. Lewes proudly claims to be "The First Town in The First State."

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.