According to the magazine, Son Doong Cave is now the largest natural cave in the world, created by a underground river under a limestone mountain range about 2-5 million years ago. The cave is 150 meters in width, over 200 in height and at least 5 km in length.
The top 12 caves in the world in pictures:
Son Doong Cave, Vietnam.
Morakot Cave, Thailand. Also known as the Emerald Cave, visitors must swim 230 feet in complete darkness to reach the cave's private beach, which is walled in on all sides.
The world-renowned Waitomo Glowworm Cave in New Zealand is home to the Arachnocampa luminosa, a worm that emits its own light. Visitors can take a boat ride through the caves and see the glowworms, which look like tiny stars in the darkness.
Some of the most interesting caves in the world are the Crystal Caves of Naica, in Mexico, which were discovered in 2000. The immense crystals are believed to have grown for about 500,000 years due to the chamber's unique conditions.
In Thailand's Phraya Nakon Cave is a pavilion built by King Chulalongkorn in 1890. It's roughly 200 miles south of Bangkok, and one of the most photographed caves in the world.
The Blue Grotto, or Grotto Azzurra, is one of the top attractions in Capri, Italy. The stunning blue water of the cave was a favorite swimming destination of Roman emperor Tiberius, who decorated it with statues of the gods Poseidon and Triton.
Fingal's Cave is a sea cave on Scotland's volcanic island, Staffa. The uninhabited island is part of the National Nature Reserve and is known for its unique basalt columns that look like giant LEGO blocks.
Near China's city of Guilin is the 180 million-year-old Reed Flute Cave. The water-eroded limestone cave was a tourist attraction even in ancient times, and is today lit up by brilliant neon lights.
France's Lascaux Caves are famous for their paleolithic-era paintings, which were preserved by calcite crystals and are estimated to be 17,300 years old. The caves were added to the UNESCO World Heritage list in 1979.
The Orda Cave in Russia's Ural Mountains is the biggest underwater gypsum crystal cave in the world, with air temperatures that can reach less than −9 °F. The gypsum filters the water, which is why it's so transparent.
Visitors to Bermuda's Crystal Cave walk on floating pontoons as they traverse the 500-meter limestone cave. A favorite spot of author Mark Twain, the water is so crystal clear that you can easily see the formations 50-feet beneath the surface.
Once thought by locals to be the "Gateway to Hell, the Eisriesenwelt cave in Salzburg, Austria is one of the world's largest ice caves. During the spring, melt water seeps through the cracks in the rock and freezes into picturesque ice formations.