Abaco Islands (ăb`əkō), island group, c.780 sq mi (2,020 sq km), most northerly of the Bahamas. Also known as Abaco and Cays, the Abacos include Great Abaco (the largest), Little Abaco, and the surrounding cays. The low islands, composed mainly of coral limestone, have native pine forests. Fish and sponges are taken from surrounding waters, and tourism contributes to the economy. Great Abaco was settled by Loyalists from New York City in 1783. An extremely strong hurricane destroyed most of the islands' infrastructure in 2019.