Kōloa is an unincorporated community and census-designated place (CDP) in Kauaʻi County, Hawaiʻi, United States. The population was 2,231 at the 2020 census, up from 1,942 at the 2000 census. The first successful sugarcane plantation in the Hawaiian Islands was started here in 1835. It became a part of Grove Farm in 1948.