YouTuber mind-blown after exploring Earth's largest cave with its own forests, rivers and clouds

Vietnam is home to the world's largest cave, and one adventurous YouTuber has shared his experience of exploring its staggering depths, finding rivers, clouds, and even rainforests along the nine kilometer trek.

You'd be hard pressed to run out of fascinating sights to see across Earth, from stunning underwater cities to secret mountaintop forests that have only been revealed after thousands of years of ice began to melt.

YouTubers often take it upon themselves to find and explore these rarely seen sights, and awe-inspiring videos have let us see cursed Italian islands and remote Alaskan towns all from the comfort of our homes.

One of the most intriguing recent videos though involves the exploration of the world's largest cave, and you'll be shocked to find out what's inside the extraordinary depths of this nine kilometer behemoth.

Uploaded by keen explorer Rhi Çenet, who makes it his mission to discover many of the world's hard-to-reach places, the video details Vietnam's Son Doong cave, which has been officially recognized as the largest of its kind on Earth with a volume of 38,500,000 cubic meters.

It takes Ruhi and his team four whole days to go from one end of the cave to the other, and it was only made possible through Oxalus, who are the only authorized agency allowed to explore Son Doong due to the safety of both explorers and the cave itself.

Immediately upon entry you're greeted with the uncompromising depths that this particular cave stretches so, as at its peak it reaches 150 meters below the surface - equivalent to an entire 40-story building.

The cave was likely formed following the erosion of limestone within the Earth, as acidity from rain caused it to break down and create the magnificent structure underground.

Its depths alone are far from the only interesting aspect of Son Doong though, as it features several unique properties that you wouldn't expect to find in a cave underground.

The depths inside Son Doong are up to 140 meters below the surface, and feature mind-blowing rock formations (YouTube/Ruhi Çenet)

Firstly, 'clouds' can technically form inside the cave in the areas between the 'inside' and the 'outside' where holes have formed above, allowing light and air to break through.

Ruhi explains that "the temperature difference between the outside and the inside of the cave forms mist and clouds inside the cave," which is certainly a strange sight to come across on your travels deep underground.

What these massive holes above also allow is the formation of rainforests, where life is capable of growing due to the extremely damp conditions too. Trees that are formed inside of Son Doong are noticeably thinner and taller than those above ground too, as they have intentionally grown in a way to stretch as close to the light far above as possible.

Finally, animals are not only found in the rainforest - where monkeys are constantly climbing between the trees above you - but also deep below in Son Doong's rivers.

Ruhi came across both fish and insects that have evolved specifically to cater to the dark conditions inside of the cave, to the point where they're completely blind and don't react to any surrounding movement, shadows, or light.

Remarkably, Son Doong was only discovered a decade and a half ago in 2009 after a local resident stumbled upon its entrance, so it begs the question as to how many other fascinating (and huge) parts of our planet are still hiding in plain sight.