Seaside Park is a borough in Ocean County, New Jersey, United States. As of the 2010 United States Census, the borough's population was 1,579, reflecting a decline of 684 (-30.2%) from the 2,263 counted in the 2000 Census, which had in turn increased by 392 (+21.0%) from the 1,871 counted in the 1990 Census. Seaside Park is situated on the Barnegat Peninsula, a long, narrow barrier peninsula that separates Barnegat Bay from the Atlantic Ocean.
The first inhabitants of the barrier island were Lenape Native Americans who came in search of fish, crabs, clams, and scallops. They called this area "Seheyichbi," meaning land bordering the ocean. The Atlantic Ocean provided more than food; these people began using shells in place of wooden beads as their form of currency. These Native Americans, who stayed during the summer and went inland for winter, were part of the principal Algonquian tribe that lived mainly on and around the North American Seaboard. The Algonquians in New Jersey called themselves "Lenni Lenape", which means "original people."
What is now Seaside Park was a section of Dover Township (now known as Toms River Township) until the creation of Berkeley Township in 1875. The area then became known as the Sea Side Park section of Berkeley Township. Over the next 25 years, lots were sold, houses and roads were built, and the population of Seaside Park began to grow.