Seaworthy.com

 The chart and following text are from The Leeward Islands Guide by Stephen J. Pavlidis

This 37 square mile island, the dual nation of St. Martin/Sint Maarten, is the smallest island in the world to be divided by two sovereign powers.  The island is usually called St. Martin, but in reality the French side is St. Martin and the Dutch side is Sint Maarten.  In practice, St. Martin is used when referring to the entire island and Sint Maarten is used when referring only to the Dutch side.  The island itself is in such a convenient location at the northern tip of the Leeward Islands that it can be used as a base for cruises to Anguilla, St. Barth’s, Saba, Statia, St. Kitts, Nevis, Redonda, and Montserrat.
    
The people of St. Martin/Sint Maarten are a blend of many cultures, not only the French and Dutch, but also Turks, Israelis, Palestinians, South Africans, Canadians, Americans, and folks from every Caribbean island as well as over 80 other nationalities, a true melting pot.  Although both sides of St. Martin/Sint Maarten are very casual about traveling back and forth, there are several subtle differences other than which language is spoken.  For instance, the French postal system is cheaper and more efficient than the Dutch postal system and phone calls to the U.S. are cheaper from the French side than from the Dutch side.