Seaside is a city in Monterey County, California, USA, with a total population of 31,696 as of the 2000 census. Seaside is the home of California State University, Monterey Bay, which is on the site of the former Fort Ord. Seaside apartments for rent comparison page shows most up to date rent information on Seaside apartments and houses. Rent information is obtained from multiple rental sources but we cannot guarantee their accuracy.