“Limestone peaks, waterfalls, deep river gorges, virgin forest -- and at least 400 more caves,” is how Liz Boulter in The Guardian describes the Phong Nha caves region. “Tectonic uplift and changes in sea-level over time have created a complex and extensive underground network” that includes Hang Son Doong, the world’s largest cave,” explains Travelfish. “Hang Son Doong is five kilometres long, with sections large enough to house an entire New York City block with 40-storey skyscrapers,” but before you “talk yourself into splurging on the required US$3,000 trek,” know that only 500 spots are available each year and “it’s sold out more than a year in advance.” And also be aware, adds Boulter: “it’s a gnarly five-night wild camping trek over pathless terrain, open only to those who can prove they’re scarily fit and won’t freak out if lowered by rope into pitch-black yawning chasms.”
But you can visit beautiful Phong Nha Cave “with a little less cash and advanced planning,” advises Rough Guides. It’s closest to Phong Nha town “and only accessible by dragon boat from the little jetty,” while Dark Cave (Hang Toi) “involves a zip line, a muddy exploration, a cold swim and a short kayak trip.” The Paradise Cave is the only cave in Phong Nha that can be explored without an arranged tour, explains Big World Small Budget. “Once inside the cave, gasp at the beauty as your eyes adjust and descend down the stairs into the darkness,” then take an “easy 1km stroll along a boardwalk” to see some of the “most breathtaking stalactites and stalagmites in the park.” Other caverns, such as Hang Va and Hang En, “require some demanding trekking,” adds Rough Guides.
And have a look at this “otherworldly footage”. Ryan Deboodt decided there was only one way to capture the stunning scenery of the world's largest cave, explains Indy100 -- “by drone.” Taken near the entrance of the cave and then at two openings that allow in natural light at 2.5km and 3.5km inside, “the high definition footage shows the dramatic rock formations, verdant surfaces and underground rivers that many people would otherwise never be able to see.” And if you want to see more breathtaking images, take a look at this Smithsonian photo series.