“Tiankeng,” incidentally, means “Heavenly Pit” or “Sky Hole.” They named it well.
Three small holes lead down into the giant Majlis al Jinn
Except for three relatively small holes, the Majlis al Jinn in the Gulf state of Oman is completely closed off from the sky.
We wouldn’t have known about it had a pair of married geologists not wondered about said holes in aerial photographs, and trekked through the wastes to investigate.
So upon shimmying into what seemed to be just a series of wide-ish crevasses like this...
…They ended up finding, to what we can only imagine was their incredible surprise and elation, that they opened up into this:
The Majlis al Jinn – the “meeting place of the Jinn,” spiritual beings popularly known to western dwellers as “genies” – was the second largest underground cavern in the world when those intrepid geologists stumbled upon it (of course it was known to locals since forever). It’s since dropped to around ninth place, but it’s still spectacular, at 120 m deep and 310 metres at its longest.
It seems those three relatively small holes let in just enough sun and moonlight to create the impression of an eerie subterranean world, so it’s not surprising that, as usual, spelunkers and extreme sports enthusiasts began to flock to it.
The result? The Omani government closed the cave to the public in 2008, citing high profile, but illegal base jumping stunts by Red Bull and other corporations as being damaging to the site.
Red Bull, at least, countered that it was all above board, since their particular 2007 dive, with noted daredevil Felix Baumgartner, had been well advertised and known to Omani media, and that Baumgartner’s team included experts that helped minimize the impact.
Regardless of what the truth is, the cave remains closed for now, although the Omani tourism ministry says they’re working on re-opening the cave with more tourist-friendly access paths and attractions.
We can’t wait.
Mexico's Cave of Crystals is unbelievable (and dangerous)
No Genies in this cave beneath a mine in Mexico, but you’d be forgiven for wondering whether you should look over your shoulder to find Superman sternly demanding what you’re doing in his Fortress of Solitude.
You might need to be super-human to make it through the Cave of Crystals, though. The cave, which is kept drained of water by mine pumps, is around 58 degrees, with 100 per cent humidity.
Those conditions were key to forming those incredible gypsum crystal pillars (some of them are 11 m long) when the cavern was filled with mineral-rich water, but the thick air is filled with the same minerals – a serious danger to the lungs of explorers (read this account by a BBC reporter who had to wear a special suit and breath mask when he visited).
The cavern’s days may be numbered, since the surrounding mine will close eventually and the pumps keeping the chamber dry and accessible will be shut down, but geologists say the cavern may be one of many such in the region.
Hopefully future explorers will turn up another beautiful work of natural art just like it.
The Grand Prismatic Spring is a fever dream
If the Crystal Cavern is nature’s sculpture studio, Yellowstone’s Grand Prismatic Spring is nature’s surrealist hobby.
And yes, that is a real place on Earth, not an alien landscape or graphic artist’s pet project.
It’s a 37-metre-deep hot spring, with the water gushing to the surface at a temperature of 70C. Those vivid colours are mats of specialized bacteria adapted to survive in the high-heat environment of the spring.
Aside from the traditional green cholorophyl, the bacteria are infused with other pigments called carotenoids, which change colour based on the intensity of the sun, and how near the bacteria are to the centre of the spring.
The centre, meanwhile, is an intense blue because the water scatters light the same way lake or ocean water does.
It couldn’t be another bacterial trick … the heat in that location is just too much to support any kind of life, bacterial or otherwise, so if you ever go visit, don’t worry about taking your swimsuit.