(Source: CNN)

The world’s largest cave is ranked third among the worldwide bucket-list trips for 2019 by the renowned UK-based travel guide magazine. 

“The incredible depths of the world’s largest cave lures in travellers who want a true adventure. But the arduous journey into this subterranean site makes booking a trek essential,” Lonely Planet wrote.

“The major tour operator that takes travellers inside, Oxalis Adventure Tours, says on its website that less than 300 spaces remain for 2019 tours. If you want to make it happen book soon – or get on the waiting list for 2020,” it said.

A four-day expedition costs 3,000 USD. Son Doong, part of the Phong Nha-Ke Bang National Park in central Vietnam, has been in international spotlight since it opened to tourists in 2013. The New York Times has named it among the world’s top eight travel destinations, while the National Geographic has called it a "natural wonder."

The Inca Trail in Peru tops Lonely Planet’s list, followed by Burning Man in Nevada of the US.