From Sandy Estabrook's Guide to the Abacos, Bahamas

Abaco Islands Ferry Schedules

From Marsh Harbour Ferry Dock on Abaco Sound. to Elbow Cay (Hope Town), & Man-O-War. Guana Cay & Scotland Cay Ferries leave from The Conch Inn Marina

From Treasure Cay ferry dock mainland Abaco near the airport to Any point on Green Turtle Cay. Leave from the Ferry Dock near the airport.

From Treasure Cay At the Treasure Cay Resort excursions to Guana, Man-O-War & Hope Town, From the Treasure Cay Resort Dock T1, Wednesdays and Sundays

Drive from Florida to Abaco, even Nassau! As of December 2011 it is now possible to take a ferry from Ft. Lauderdale to Freeport Grand Bahama via Baleária Bahamas Express. The Announced Min price $49.00.
It has always been possible to get from Freeport Grand Bahama to Nassau via the Abacos without having to fly by using two more ferries and with lots of driving. I wouldn't say it is practical nor can attest to the reliability of the services so check them out first.

There is a twice daily ferry from Crown Haven, at Abaco northern most settlement to Mclean's Town on GRAND BAHAMA ISLAND which is about 50 miles from Freeport. Supposedly there are busses from there to Freeport. They can be reaches at Pinder's Ferry Service 242-365-2356.

And from Abaco's southern most settlement at Sandy Point there is another ferry service to NASSAU. It too has a connecting bus service from Marsh Harbour. Check their website BahamasFerries.com