A petition to save the world’s largest cave from a proposed cable car has garnered over 25,000 signatures online.

The Hong Son Doong cave in Phong Nha-Ke Bang National Park in Quang Binh province in Vietnam, is one of the world’s most famous natural wonders.

The cave extends close to 9 kilometres underground and has its own ecosystem, jungle and river.

The cable car project was proposed by the Sun Group in 2014, but has been stalled for two years due to opposition by environmental activists.

The Sun Group has now found a financial backer for the project in the FLC group.

Environmental activists are calling on the Vietnamese government to block the proposal.

They say excessive development would disrupt the area’s ecosystem and damage the natural landscape.

The proposed cable car would stretch through the national park and traverse parts of the remote cave, potentially bringing in thousands of tourists a day.

The cave was first discovered in 1991, but was lost again until it was explore in 2009.

– TiVi Tuan-san