I visited the outskirts of Carrasco from two sides - the Villa Tunari side to see the Oilbird caves as well as from the Incachaca side for more birds. Unfortunately the old road (known as 'Camino de las Nubes') is no longer passable, as it would have been a hell of bike ride. As I understand it, the road is barely passable by foot. Either way, the park is one of those few places where nature is winning. Man has limited access, but what access one does have is excellent. Although I never understood a word that our guides were talking about - they conveyed a sense of love and respect for the environment they were in. Getting great views and photos of the Oilbirds topped off an excellent afternoon trip.
The trails to visit the Oilbird Caves are open at 08:00 and 15:00. Costs are divided by the number of people present (split differences between foreigners and locals). In other words, it is no use being one foreigner with 20 locals - you'll pay steeply!
If you own or manage Carrasco National Park, register now for free tools to enhance your listing, attract new reviews, and respond to reviewers.