Drive west towards Santo Domingo and pick up the Samana highway just after the airport. Hang to the right and watch for the Caribe Tours Buses. Yes, you can miss it. Try Google maps or asking on the road. You have to get to sorta shoulder road. Sorry, I do not come at it from that direction. But once you hit the highway, it is just a beautiful drive up to Samana. I think the tolls are around 450 pesos.