Don’t forget your passport, of course. You will have to pay a $10 fee to get your tourist card when you arrive. If you don’t hold a DR passport but were born there, you don’t need to pay that fee. My partner discovered that after he paid the $10. Not a big loss, but you can use that to buy yourself a nice cold Presidente, the local beer. Ask for a “Presidente vestida de novia” (Presidente in a wedding dress, referring to the white frost of an ice-cold beer).