You will need to take a taxi from Barahona ......
.....It will be about a 30 minute ride. Enjoy the area...San Raphael falls are great (just keep climbing). Great fish dinners on the beach. The hotel really is a "loser" though. They just don't get enough traffic to really to keep it "going" the way a newer hotel/resort should be run. I do understand there is discussion about reopening the Riviera Hotel in Barahona. I did not see it open when I was by there 3 weeks ago, but when it was open in the past it was my definite favorite in the area.
Suerte! Dave