The resort town of Boca Chica is a 15-minute drive from the airport. If you've booked a package tour, you won't have to worry about getting to Boca Chica, as there's a shuttle bus waiting for you at the airport.
If you have to choose your own means of transportation, you can get to the long-awaited beach area by cab. It will cost around 1200-1500 DOP. A bus is a more budget-friendly option. It runs several times a day, and a single ticket will cost around 200 DOP.