The United States requires that a valid passport be presented upon return to the United States from the Dominican Republic if you travel by air. If you travel by cruise ship and one destination stop is the Dominican Republic, you must have a government photo issued identification and citizenship documentation. However, for ease of travel with today's heightened security, travel with a passport is a must.
Traveler's to the Dominican Republic are required to purchase of visitor's visa, good for 60 days, for $10 as of September 2010. You can purchase a visa at the airport when you arrive. You may also purchase a visa prior to entering the country Dominican Embassy in Washington or Dominican Consulates, but it is not necessary. If you stay beyond 60 days, however, you must request an extension at the Migration Department in Santo Domingo.
Although the dollar can be used in some tourist locations in the Dominican Republic, some smaller shops and vendors may only conduct exchanges with the peso. A dollar will render approximately 37 pesos as of September 2010. The dollar can be exchanged at the airport, but you will get a better rate at the bank and at some local businesses.