when we have visitors they use a company run by a guy called james, with an office in playa dorada. admittedly he cannot even pronounce jarabacoa correctly (he pronounces J like J in jackson, not like H) but he offers very good reliable service.

i have his latest flyer and it says:
santiago-jarabacoa: full day tour, tuesday and friday. the trip includes a visit in santiago, then cigar factory and a pottery workshop. later on jarabacoa ranch with horse riding, lunch and a short jeep safari to do swimming and climbing at a waterfall. 55 bucks per person, includes lunch.
river rafting: mon, tues, wed, fri, sun. full day, with lunch. rafting down jimenoa river. 75 dollars.
a friend of mine - an excellent swimmer - did the river rafting trip and she loved it. said it included some basic training and then off to the adventure. capsized at least once

but said she had a great time and a huge adrenaline rush.
i do not own that business and they did not pay me to advertise them. just telling about what i had experience with. you will find other companies selling the same trips at comparable prices. your choice entirely.
james is located in playa dorada, in front of pizza hut. 809 320 1076.