~ the highest mountain range in the RD is Pico Duarte...google "Eco-Tours" they have hiking tours and lodging information...its not cheap thought a three day hiking tour will run about us$450.00 per adult...
The drive to La Ci?nega from Boca Chica is about 3 1/2 hours. La Ci?nega is the most popular jump off point for the hike to Pico Duarte. You can have it coordinated, which has already been mentioned or you can do it yourself - hiring a guide and staying at the park service refuge in La Ci?nega the night before you begin the hike.
If you are serious about going and need a guide's details, PM me.