Mill Basin is a residential neighborhood in southeastern Brooklyn, New York City. It is on a peninsula abutting Jamaica Bay and is bordered by Avenue U on the northwest and the Mill Basin/Mill Island Inlet on its remaining sides. Mill Basin is adjacent to the neighborhood of Bergen Beach to the northeast, Flatlands to the northwest, Marine Park to the southwest, and Floyd Bennett Field and the former Barren Island to the southeast. Mill Basin also contains a subsection called Old Mill Basin, north of Avenue U.

Jamaica Bay is an estuary on the southern portion of the western tip of Long Island, in the U.S. state of New York. The estuary is partially man-made, and partially natural. The bay connects with Lower New York Bay to the west, through Rockaway Inlet, and is the westernmost of the coastal lagoons on the south shore of Long Island. Politically, it is primarily divided between the boroughs of Brooklyn and Queens in New York City, with a small part touching Nassau County.