Green Turtle Cay is located in Abaco, Bahamas approximately 170 miles due east of Palm Beach,  Florida.  Fly to Treasure Cay Airport (TCB) and take a short taxi ride to the dock for the Green Turtle Ferry.

The flight from the east coast of Florida takes only about 1 hour

  The 5 minute taxi ride from the TCB airport costs $6 for two people and the GTC ferry costs $8 per person

Another travel option is to fly to Marsh Harbour Airport (MHH) in Abaco, which has more flights available, and take a 30 minute taxi ride costing $60 for 2 people to the Green Turtle Ferry. 
Remember to allow travel time back to Marsh Harbour from the Green Turtle Ferry for your departure. 

When connecting to one of the charter services from a major US carrier always give yourself a minimum 2 hour layover in Florida to collect baggage, especially if you need to get to The Jet Center in Fort Lauderdale from the main airport terminal.  On return flights to the United States, a 3 hour layover is advised to allow enough time to clear US customs and allow for any flight delays from the Bahamas.