Cable-car system proposed for Vietnam's cavernous Son Doong cave.
Son Doong cave, Vietnam.

A cable-car system  incorporating 30 supporting towers is planned for Vietnam’s Son Doong, the world’s largest known cave. Located in the Unesco-recognised Phong Nha-Ke Bang National Park, Son Doong is 5km long and in parts 150m high, containing underground rivers and a subterranean jungle. It was first opened to a limited numbers of tours in 2013. Local government states the cable-car system would not harm the cave and that the plan would not go ahead without Unesco endorsement. Read more:

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