The Damajaqua Cascades (27 Waterfalls) are a series of waterfalls about 45 minutes from Cabarete, or 25 minutes from Puerto Plata.  An entrance fee of 460rd covers everything you need (shoes, helmet, life jacket, guide) although you can choose lesser packages which include fewer waterfalls if you're not up for the full challenge.  In order to enjoy the canyoning adventure, you hike up the mountain for about an hour until you reach the falls and work your way back down the river by jumping and sliding through pools of water - this can be challenging so you shouldn't have any physical limitations or fear of jumping from ~10-20 ft falls.  After rain, the water is a little murky as well as higher/faster than normal. It's clear and gorgeous other times.

There is a nice visitor center with bathrooms, a bar and, of course, a gift shop.

 http://www.27charcos.com/index.php 

It is a little challenging getting there but that's part of the fun.