St. Barthélemy has a small airport known as Gustaf III Airport on the north coast of the island that is served by small regional commercial aircraft and charters. The nearest airport with a runway length sufficient to land a typical commercial jet airliner is on the neighboring island of Sint Maarten: Princess Juliana International Airport, which acts as a hub, providing connecting flights with regional carriers to St. Barthélemy. Several international airlines and domestic Caribbean airlines operate in this sector.
How many domestic Caribbean airlines are there?