Sint-Maarten has an international airport (one of the largest in the Caribbean), which has DIRECT FLIGHTS to major US and Canadian cities:
New York (NY), Newark (NJ), Philadelphia(PA), Boston (MA), Charlotte (NC), Chicago (IL), Atlanta (GA), Fort Lauderdale (FL), Miami (FL), San Juan, Montreal, Toronto, Edmonton, etc.
The major airlines serve Saint-Martin: American Airways, Continental, US Airways, United, Delta, Jet Blue, Spirit Airlines, Air Canada, Air Transat, Skyservice, etc.
(For example, a round trip ticket from New York/Saint-Martin is around $400).
For other cities, a connecting fight is necessary.