If you have driven here before, you should not have a problem.
If you haven't, then I suggest you take public transportation to the peninsula and then think about a rental.
Taxi from airport to Caribe Tours or Metro.
However this is dependent upon your time of arrival as the last bus to Samana leave fairly early.
If you must drive-not recommended-here is a set of directions that will help
Out of the airport, follow signs to Santo Domingo. Stay in the middle or left lane until you cross the bridge (about 1/2 hour or 45 minutes depending on traffic.
Take the "ELEVADO".
When you come down off the elevated roadway, stay in the left lane, or middle lane for one light. At the next light (Tiradentes) turn right. Go to the next major intersection ( J.F. Kennedy (an overpass)) go under the overpass and go left.
Stay in the left lane and go over the next overpass and go to the center lane. DO NOT TAKE THE NEXT OVERPASS. You are now pointed North towards Santiago and Samana.
Have RD$30 pesos in coins ready for the toll booth.
After you pass Bonao, you will come to the intersection that leads to San Francisco de Macoris. Go right, just past the TEXACO station.
In SFM watch for signs saying NAGUA. Follow them.
In Nagua, go right to Sanchez.
In Sanchez, go left to Samana.
Easy huh?
HB