From the US department of State

The crime threat in Sint Maarten is generally considered medium, and travelers should always take normal precautions when in unfamiliar surroundings. Street crime remains a concern on Sint Maarten. Valuables, including passports, left unattended on beaches, in cars, and in hotel lobbies are easy targets for theft. Visitors should leave valuables and personal papers secured at their hotel. Burglaries and break-ins are common at resorts, beach houses, and hotels. Armed robbery occasionally occurs. The American boating community has reported a handful of incidents in the past, and visitors are urged to exercise reasonable caution in securing boats and belongings. Be especially observant when visiting isolated areas. U.S. travelers should have a copy of their valid U.S. passport in a secure location in case their passport is stolen.

Car theft, especially of rental vehicles, can occur. Incidents of break-ins to rental cars to steal personal items have been reported by U.S. citizen tourists. Damages may not be fully covered by local insurance when a vehicle is stolen. Be sure you are sufficiently insured when renting vehicles, jet skis, and other equipment.

VICTIMS OF CRIME: If you or someone you know becomes the victim of a crime abroad, you should contact the local police and the nearest U.S. embassy or consulate. We can:

Replace a stolen passport.
Help you find appropriate medical care if you are the victim of violent crimes such as assault or rape.
Put you in contact with the appropriate police authorities, and if you want us to, contact family members or friends.
Help you understand the local criminal justice process and direct you to local attorneys, although it is important to remember that local authorities are responsible for investigating and prosecuting the crime.
The local police emergency line in St. Maarten is “911.