In recent years there has been a flurry of bi-lateral trade deals between countries and the emergence of regional trading blocs. For example, the European Union now has over 30 separate international trade agreements including those with countries such as Colombia and South Korea.
Since 2008 all US citizens MUST have a US passport to be allowed to enter the United States. If your aunt travelled to Jamaica with just her US naturalisation certificate, she would not be able to board her plane back to the US. She would have to come to the Embassy to apply for a passport in order to return home. Issuing a new passport takes at least a week, so this could extend her holiday much longer than she had planned. The good news is that she can apply for a US passport before she leaves the United States.
Please note that travel anywhere else in the world requires a valid passport from your country of citizenship and subjects you to any documentation, visa and health requirements of all countries visited. Bermuda: Non-U.S. / Canadian citizens may be required to obtain an entry visa for cruises that visit Bermuda.on-U.S. / Canadian citizens who do not require Schengen visas must obtain a multiple-entry type visa before traveling. U.S. and Canadian citizens do not require a Schengen visa. Special Requirements For Visits To Other Countries: This summary only highlights some of the most common cruise documentation requirements.