According to the park’s management board, the survey, conducted from March 21 to April 11 with a team of British caving experts and local support staff, explored 29 caves in total, including 26 new sites and extensions of three known caves, with a combined length of 13,643 metres.

Among the notable discoveries are Thien Cung Cave, the longest at 4,206 metres, Nuoc Lan Cave at 2,721 metres, Ma Drom Cave at 1,257 metres and Cha Ngheo Cave at 583 metres. Many feature complex structures and high scientific value.

The findings highlight the park’s extensive karst system, with both deep vertical shafts and expansive horizontal caves, reinforcing its outstanding global value recognised by UNESCO for geology, geomorphology and biodiversity.

Cha Ngheo Cave, in a strictly protected zone, features a deep vertical shaft with waterfalls and underground streams, suggesting further extension. In Sinh Ton Valley, the entrance to Thien Cung Cave may mark an ancient flow of the Hang Toi River and links hydrologically to the Chay River.

In Kim Phu Commune, three caves with underground streams were identified behind Ruc Mon Cave, including sites suited for adventure tourism. Mo Roo Cave, about 500 metres long and easily accessible, was also flagged for tourism, while Nuoc Lan Cave shows seasonal flows of hydrological interest.

The survey also urged upgrades to existing sites, including optimising lighting at the Son Boi cave complex and improving links between caves and surrounding routes.

Authorities said the findings mark a significant step for research, conservation and sustainable tourism, opening scope to diversify offerings and boost the park’s appeal.