Martinique is an overseas department of France so technically it is part of the European Union. This means that the same rules apply to visit Martinique as if traveling to France: US, Canada, Australia, and New Zealand citizens do not need a visa, and will be automatically granted 90 days tourist access upon arrival. Visitors from other EU states do not need a visa either and are free to stay as long as they wish.
Health and Safety
There is no risk of yellow fever in Martinique, although a valid certificate is a requirement to enter. You should get this vaccine six to eight weeks prior to your intended travel date. Although Martinique has high healthcare standards in line with France and the EU, it is recommended you get the following routine vaccinations before you travel: hepatitis A and B, MMR, rabies, tetanus, tuberculosis, and typhoid.
There is absolutely no malaria on the island, so preventative medicine for this is not needed. However, mosquitoes do exist and Dengue fever is prevalent, which cannot be treated, so it is recommended to use bug spray to prevent bites. There is the risk of contracting schistosomiasis if swimming in fresh water areas, which is best avoided, but salt water or chlorinated pools are fine.
Martinique is a very safe country although care should be taken to look after valuables on the beaches. Don't carry large amounts of cash or jewelry. It is best to leave all valuables and your passport in the safe in your hotel. Theft from rental cars is also a small concern so try not to leave your valuables inside in plain sight, even if the vehicle is locked.
Being in the tropics, Martinique is at risk of violent storms and hurricane season lasts from June to November each year, although rarely hit the country directly. Still, it is best to avoid remote areas at this time, and always check weather updates by visiting the US National Hurricane Center website at http://www.nhc.noaa.gov/