Depends on the time of year as well, you can go Whale watching, scuba diving in Samana. You could travel to the mountains and hike, or trek as well as ride your bike through the trails of the tropical forest of El Limon. Try the Northern shores of Playa Dorada, Surf the waves, windsurfing, Kite-surfing in Caberete. i am sure at this time of year you could catch some huge swells it will be totally awesome. Swim with the Dolphins in Puerto Plata, although the best scuba diving and snorkeling are done in Sosua. Besides all that there was this place i always wanted to go they say it has a Magnetic force where cars roll up hill the location is in Barahona the place is called Polo Magnetico, is it an illusion or a mystery?