1 definition found neptune beach - U.S. Gazetteer (1990) : Neptune Beach, FL (city, FIPS 48100) Location: 30.31474 N, 81.39374 W Population (1990): 6816 (3265 housing units) Area: 6.3 sq km (land), 11.4 sq km (water) Zip code(s): 32266