"Of all the exciting developments that have occurred in the last decade, the new travel landscape is definitely high on the list. Certain countries have opened up to tourism, some cities have become safer for visitors and a handful of new nations have even been born," the website said.

"Son Doong Cave in Viet Nam is the biggest cave in the world. The cave is situated in Central Viet Nam‘s Phong Nha-Ke Bang National Park, and before the cave's first exploration in 2009, the national park wasn't exactly a tourist attraction.

"All that has and will continue to change rapidly with the exploration of not only Son Doong, but other massive caves around the national park. The enormous underground caves are practically otherworldly in their size and shape, to say nothing of the bizarre structures, the rivers and, in the case of Son Doong, the forests that dwell inside them.

"Phong Nha-Ke Bang National Park will only see more travellers as these caves become more accessible, so get there fast!"

Others on the list are Cuba, Myanmar, Montenegro, Sri Lanka, North Korea, Papua New Guinea, Downtown Los Angeles, Iran, and Brooklyn in New York. 

VNS