Aside from snorkeling and scuba diving, what other activities could a group do, to have lots of fun. Is surfing possible on the North coast beaches?
I think this link can help you to find out some information about surfing in DR.Check it out http://dominicanrepublicsurf.com/
Lots to do including surfing, kite boarding, wind surfing, paddle boarding among the water sport activities. Especially in the Cabarete area.
Lots of other things to do as well. Here are some sites to look at:
iquana mama http://www.iguanamama.com/
outback safari http://www.outbacksafari.com.do/
Ocean world www.oceanworldadventurepark.com
Monkey Jungle and zip line: http://www.monkeyjungledr.com (my favorite)
James in Playa Dorada: https://sites.google.com/site/toursbyjames/
Bavaro runners www.bavarorunners.com/