Nuoc Mooc is a short eco-trail in the western section of the national park, less visited than the main cave circuit, that leads through jungle to a series of spring-fed swimming pools. The water is clear and cold — unusually so in this climate — and a vivid blue-green from the mineral content of the limestone geology. You can swim in the main pool, then walk deeper along the trail to smaller pools and waterfalls.
The area is also good for birdwatching: the primary forest around Nuoc Mooc holds a variety of species not easily seen closer to the village, and the early morning, before tourist groups arrive, is quiet enough to hear the forest. The trail takes about two hours return at a gentle pace, longer if you linger at the swimming holes. Entrance fee applies; the park charges a small fee at the trail entrance.