Mount Sinai South Nassau is a hospital located in Oceanside, NY. The facility was opened in 1928 and has undergone rapid expansion since. It is the Long Island flagship hospital for the Mount Sinai Health System.

Oceanside is a hamlet and census-designated place (CDP) located in the southern part of the town of Hempstead, Nassau County, New York, United States. The population was 32,109 at the 2010 census.