The US State Department issues warnings for many countries, including Mexico. It is important to be aware of them and take them into consideration when planning your trip. Generally the warnings are based on information about crime, political strife or civil unrest in a particular area and should not be considered representative of the whole country. If you plan on traveling to a specific city or region that has issued a warning, you should research the area further before deciding to go. Isla Mujeres is one of the safest places in Mexico.