South Amboy is a suburban city in Middlesex County, in the U.S. state of New Jersey, located on Raritan Bay. As of the 2020 United States census, the city's population was 9,411, an increase of 780 (+9.0%) from the 2010 census count of 8,631, which in turn reflected an increase of 718 (+9.1%) from the 7,913 counted in the 2000 census.

Raritan Bay is a bay located at the southern portion of Lower New York Bay between the U.S. states of New York and New Jersey and is part of the New York Bight. The bay is bounded on the northwest by New York's Staten Island, on the west by Perth Amboy, New Jersey, on the south by the Raritan Bayshore communities in the New Jersey counties of Middlesex and Monmouth, and on the east by Sandy Hook Bay. The bay is named after the Raritans, a branch of the Lenape tribe who lived in the vicinity of the bay and its river for thousands of years, prior to the arrival of Dutch and English colonists in the 17th century.