Covered the caves for the Playa Dorada magazine in 2006. This what I wrote:
"About 1 km west of central Cabarete, and a 1 km walk from the main road, are the caves that form part of the Natural Monument Cabarete and Goleta Lagoons (also known as El Choco National Park), which offer an alternative to all the sun and surf of Cabarete.
You walk through lush tropical jungle, and then up man-made steps. Then through to a big passage and suddenly you are told to walk down, down under. It's so cool, but then weird. All of a sudden you are in a natural jacuzzi, a crystal clear pond in the middle of the earth.
The caves are the result of geological formations known as Caribbean karsts that are found in relatively flat landscapes and are made up of sinkholes, sinkhole ponds, disapearing streams, crystal clear springs and underground caverns often filled with water.
There are several caves in the area, some a one-hour hike and others a three-hour hike away. Horse ranches take visitors on tours into the park to observe the numerous edible tropical fruit plants and the vast variety of birds.
This area is a large protected extension of around 77.5 square kilometers (48 sq. miles) of lagoons, pasture and low mountains, amidst rainforest and several caves."
To answer your question: Yes, you can just drive there. You could hire one of the locals to take you to the underground watering hole, or you could just follow the trails. There may be many aspirants to guides, but I would think they would understand you can only hire one person. The caves do not get many visitors, so I would think that you will not be "mobbed" by people trying to take you on a tour.