Marsh Harbour is a town in Abaco Islands, Bahamas, with a population of 6,283 as of 2012.

The Abaco Islands lie in the northern Bahamas, about 193 miles east of Miami, Florida. The main islands are Great Abaco and Little Abaco, which is just west of Great Abaco's northern tip. There are several smaller barrier cays, of which the northernmost are Walker's Cay and its sister island Grand Cay. To the south, the next inhabited islands are Spanish Cay and Green Turtle Cay, with its settlement of New Plymouth, Great Guana Cay, private Scotland Cay, Man-O-War Cay, and Elbow Cay, with its settlement of Hope Town. Southernmost are Tilloo Cay and Lubbers Quarters. Also of note off Abaco's western shore is Gorda Cay, now a Disney-owned island and cruise ship stop renamed Castaway Cay. Also in the vicinity is Moore's Island. On the Big Island of Abaco is Marsh Harbour, the Abacos' commercial hub and the Bahamas' third-largest city, plus the resort area of Treasure Cay. Both have airports. A few mainland settlements of significance are Coopers Town and Fox Town in the north and Cherokee and Sandy Point in the south. Administratively, the Abaco Islands constitute seven of the 31 Local Government Districts of the Bahamas: Grand Cay, North Abaco, Green Turtle Cay, Central Abaco, South Abaco, Moore's Island, and Hope Town.