Are you looking for trips you can make on your own, or a planned activity offered by a tour company? Assuming you are thinking of trips on your own, among your choices are:
1. Going to Cabarete for the day. It is nearby and easily reached by inexpensive gua gua or publico (publico).
2. Going to Puerto Plata for the day. Again, inexpensive public transportation readily available.
3. Spend a day in Santiago, the DR's second largest city. Take the Caribe Tours bus from Sosua to Santiago, see the city, and return to Sosua on the CaribeTours bus. Bus leave hourly from both.