Marina Bay is a mixed-use development neighborhood of condominium, commercial and entertainment facilities in Quincy, Massachusetts. It includes five housing complexes (including detached, townhouse and low-rise apartment units) and one assisted living complex, office complexes, numerous restaurants, a 685-slip marina and a seaside boardwalk. It is situated on the northwestern part of Squantum Peninsula at the mouth of the Neponset River where it meets Dorchester Bay in Boston Harbor.