I have written many times about the joys of visiting the Samana region. From January to March whales come to spawn in Samana bay. There are national parks, waterfalls, beautiful mountains, and for my money, the best secluded beaches in the Dominican Republic. Don't take my word for it, go see for yourself. It takes a little over 4 hours to get there, but some friends of mine tried another option this past weekend. I told them that there are flights that leave from La Isabela airport (small regional airport north of Santo Domingo) and they decided to give it a try. Below are some photos from their journey. Not for the faint of heart, but, if you like to be in Samana in 30 minutes (only $70 each-way!), then it is the way to go.
I like Las Terrenas, but there are many towns to visit and checkout in the Samana region. There is a large French ex-pat community in Las Terrenas, so you can get great wine and french delicacies. You can rent an ATV (all terrain vehicle) and explore the miles and miles of sandy beaches.
Warning: Samana is not a party capital. It is for those seeking relaxation and beaches!