Oceanside is a hamlet and census-designated place (CDP) located in the southern part of the town of Hempstead, Nassau County, New York. The population was 32,109 at the 2010 census.
Originally known as South Bay, the English government established a township there in 1674 called Christian Hook, basing the name on the predominant religious affiliation of colonists in the area. Land development proceeded rapidly, and oyster sales took their place as a dominant force, with the local business "Mott's Landing" becoming a favorite place to buy oysters.
In the nineteenth century, the town residents decided that "Oceanville" sounded better than "Christian Hook": it was "Oceanville Oysters" that sold, and in 1864, the new name became official. However, there was already an Oceanville in New York, so "Ocean Side," as two words, was adopted as the town's name in 1890 (this despite it not actually fronting the Atlantic Ocean, which is located a few miles to the south. It is separated from the ocean by Reynolds Channel and other marsh islands, as well as the Long Beach Barrier Island).
The Oceanside Fire Department was established in 1902. Columbia Engine Co. #1, an old firehouse, still exists, and is located at the southwest corner of the triangle where Lincoln Avenue meets Long Beach Road.
In the 1900s, the town began rapidly expanding south, building over swamps and marshes and dramatically increasing the size of the town from a small port to a large hamlet.