Son Doong, the largest cave on our planet. This cave is so massive that it has a completely self-sustaining ecosystem with its own climate conditions. Hundreds of meters underground, the clouds you're used to seeing in the sky form inside this cave. Son Doong even has an untouched prehistoric rainforest hidden far below the surface and a vast underground river. From transparent fish to colorful monkeys, over 250 endemic plant and animal species live in this underground world. Seven new animal species were recently discovered here and are unique to this place. Stretching 9 kilometers in length, this cave holds 38.5 million cubic meters of space. And its passages are so enormous that a 40-story skyscraper could fit inside and its giant stalagmites are rising like the towers of ancient cities. Walking inside, it’s impossible not to feel as small as a tiny bug. Son Doong even contains phytokarst rocks, which move towards the sun like semi-living organisms. Rare cave pearls and many other