The caves – Dai A, Over and Pygmy – are part of the Vom cave system in the park’s ecological restoration zone.

Dai A Cave, previously known as Tiger Cave, stretches 1,616 meters in length and reaches as deep as 46 meters from its opening, which measures over 50 meters in diameter.

Over Cave is located 100 meters from Dai A Cave, running 3,244 meters long and 104 meters deep, with the widest section measuring up to 125 meters in diameter.

Meanwhile, Pygmy Cave is the smallest of the three, stretching only 845 meters in length and 94 meters deep.

The caves are surrounded by primeval forests boasting high biodiversity and scenic landscapes.

Adventure-seekers taking part in the upcoming tour will trek 20 kilometers across the forests and caves over the course of three days and two nights.

The tour’s itinerary will be submitted to the administration of Quang Binh for approval, and is expected to become available as early as 2018.

The Phong Nha-Ke Bang National Park is a UNESCO-recognized World Heritage Site situated in a limestone zone of 2,000 square kilometers in central Vietnam.

The park is famour for hosting the world's biggest known cave of Son Doong, which is part of two massive karst regions with 300 caves and grottos.