1 definition found key biscayne - U.S. Gazetteer (1990) : Key Biscayne, FL (CDP, FIPS 36300) Location: 25.68995 N, 80.16535 W Population (1990): 8854 (5724 housing units) Area: 3.3 sq km (land), 0.3 sq km (water) Zip code(s): 33149