You know, there’s a funny thing about the human race: we sure like it up here on our high horses. Because we’ve invented neat things like couches, MRI machines and a McDonald’s delivery service, and other species haven’t, we think we’re all set to lord it over this planet and do as we wish.

Our scientists and explorers sometimes like to think that they know everything there is to know about this planet. That they’ve answered all of the big questions. After all, once you start cloning sheep and growing human ears on the backs of mice, where do you go from there? You’ve conquered the intellectual world.

Now, the range of knowledge we have today is just unparalleled, there’s no denying that. The research technology we have at our disposal (CERN’S Large Hadron Collider, for instance) is beyond anything we could have really imagined until quite recently. Despite this, though, it’s sometimes a little daunting just how much we still don’t know.

The reaches of space are a mystery we’re still trying to probe, but let’s think a little closer to home. Earth itself is home to all manner of curious and frightening phenomena, which all of our fancy research tech and knowledge still can’t really explain away.

What exactly do we know about the notorious and super-dangerous Elephant’s Foot at Chernobyl? Or the strictly off-limits Snake Island? Or even the humongous miles-in-diameter fungus that could conquer the planet any time it wanted? Strap yourselves in, friends, it’s going to be a bumpy ride.

25 Snake Island, Brazil: Definitely Not The Place For A Tropical Vacation

Back in my school days, I often felt that certain rules were completely unfair. As an adult, I remain a little uncomfortable with authority and conforming to rules and restrictions. Some of them, though, are imposed on us for a darn good reason.

When the Brazilian government tells us that visiting the Ilha da Queimada Grande (Snake Island) is forbidden, they’re not kidding around. The infamous island is home to the world’s only golden lancehead pit vipers, a species that boasts venom strong enough to melt through flesh.

The snake population here is estimated to be around one per square foot of island. Funnily enough, Brazilian government, restrictions or no restrictions, I think I’ll give it a miss.

24 The Elephant’s Foot, Chernobyl: That Poor Dang Elephant

The Chernobyl Disaster of April 26, 1986 is one of the most infamous incidents in human history. The reactor explosion had effects that are still felt over thirty years later, and the surrounding area may never be the same.

The explosion and its aftereffects are quite well known, but the mystery of the ‘Elephant’s Foot’ is a little less so. This is the name given to “a solid mass made of melted nuclear fuel mixed with lots and lots of concrete, sand, and core sealing material that the fuel had melted through,” so named for its wrinkled appearance.

It’s a vast glob of corium, one of the most dangerous substances on the planet, located in the area that was once the basement of Reactor No. 4. So radioactive is the Elephant’s Foot, no human could survive more than 500 seconds in its presence today, and that’s after its radioactivity is thought to have weakened to one-tenth of its original power!

23 The Great Blue Hole, Belize: It’s Just Un-Belize-able

Here’s another sight that’s simultaneously beautiful and alarming for you. The Great Blue Hole is found just off the coast of Belize, a stunning sight and the world’s largest natural formation of its kind.

A cave that flooded thousands of years ago, the Great Blue Hole is a location beloved by scuba divers worldwide. It boasts wonderfully clear waters, and at around 125 metres (410 ft) deep, it’s more than enough to test the mettle of even seasoned divers.

Not only in terms of depth, mind you, but… just look at it. it’s like someone’s filled Turkmenistan’s Door to Hell with water.

22 The Depth Of The Oceans: Here There Be Monsters!

We’ve already touched on the areas of the planet that humanity is still a little clueless about, so let’s run with that. it’s often said that we understand more about the further reaches of the solar system than we do about the depths of our own oceans, and when you check out some statistics, it’s quite clear just how true that is.

Chew on this factoid, for instance: according to The National Ocean Service, “more than eighty percent of our ocean is unmapped, unobserved and unexplored.” Considering the fact that almost three quarters of the planet is covered in said ocean, this is all kinds of alarming. What kind of species dwell down there in the murky depths, still undiscovered? What else could be down there besides?

21 Aokigahara Forest, Japan: If You Go Down To The Woods Today…

There are some places of stunning natural beauty, made all the more poignant because of an unfortunate reputation that they just can’t shake. Japan’s Aokigahara forest is definitely one of those places.

The forest is located in the shadow of Mount Fuji, and is so vast and dense that it’s nicknamed the ‘Sea of Trees.’ With the thickness of the trees and the lack of wildlife, the place is eerily silent, and the great quantities of iron in the volcanic soil often make compasses useless.

Aokigahara is a real enigma, both beautifully serene and crushingly oppressive. Stories of paranormal activity here cause many to give the forest a very wide berth.

20 The Unstoppable Bat Army

Take a moment now and consider what you think the biggest mammal migration on Earth might be.

Are you thinking of Wildebeest barrelling en masse across the plains of Africa? Maybe hordes of irritable shoppers roundhouse kicking their way to the front of the line on Black Friday? Both totally sensible guesses, but you’re way off. It’s actually bats, of all things.

That’s right, friends. As National Geographic explains, “Millions and millions of bats—giant fruit bats, to be exact—fly between the Democratic Republic of Congo and Zambia’s Kasanka National Park each year. With more than 10 million of these cat-size, mango-munching, echolocating chiropterans involved, it’s the largest known mammal migration on Earth.”

What a spectacle that must be.

19 The Humongous Fungus

So, yes. As we’ve seen, there are 10 million leathery, wrinkled cats flying through the sky every year in a great grouping. The world is full of surprises, that’s for darn certain.

Here’s another one: the largest living thing on the planet isn’t the blue whale, but… a dang mushroom.

The famous ‘Humungous Fungus’ (as its friends call it) covers a ludicrous area of 2,385 acres. It’s found in the Malheur National Park, Oregon, and is also probably the oldest living thing on the planet. Estimates place it anywhere from 2,400 to 8,650 years old.

Granted, this isn’t one enormous mushroom cap above the ground (rather a whole interconnected crowd of them), but still. This is seriously impressive.

18 The Door To Hell, Turkmenistan: Maybe Don’t Open That Door

Here’s a curious (by which I mean scary) one. Is the infamous ‘Door to Hell’ a manmade phenomenon or a natural one, you ask? That’s an excellent question, because it’s actually a little of both.

What you’re looking at is the Darvaza Gas Crater in Turkmenistan. According to The Guardian, its origins are uncertain, but it’s believed to have been created during a Soviet search for gas. The story goes that, amid fears that it may be emitting toxic fumes, it was set alight in the early seventies. If that is the case, it’s been burning ever since.

However it came about, one thing’s for sure: it’s become a scary sort of tourist attraction in its own right.

17 A certain numbered 'Area' in the United States: They Won’t Let You Ali-In

Ali-in? Ali-en? Yep, that’s one of those jokes that sounds better in your head, but heck. I’ve committed to it now.

Never mind all of that, though. We’re off to our next stop, the deserts of Nevada. Here, you’ll find a site that’s simultaneously world famous and a completely unknown entity.

As reported by Atlas Obscura, this base has been a test facility since the fifties. Nobody quite knows what happens here, but it's become central in conspiracy theories about UFOs and aliens. While the guards don’t want anybody near the place, tourist dollars still have to be earned, so various extra-terrestrial-themed attractions and hotels have popped up in the area.

16 The Bosnian Sphere, Bosnia: That’s One Baffling Ball

This is exactly what I was talking about in the introduction. Just when mankind starts to feel a little complacent, a little too accomplished, along comes a mystery to prove that we’re just scratching the surface when it comes to understanding our planet and its/our own history.

In 2016, a mysterious spherical object was discovered near Zavidovici, Bosnia. It came to be known as the ‘Bosnian Sphere,’ and rumours and theories still circulate about it. Local archaeologist Semir Osmanagic theorised that the sphere could be evidence of an advanced civilisation, though others have dismissed his claims. It’s a fascinating object nonetheless, with its neat shape and oddly high iron content.

15 The Crooked Forest, Poland: The Strangest Trees You Ever Saw

For our next stop, we’re going to cross over to Poland. There, in an otherwise entirely ordinary forest near Gryfino, stand a grove of peculiar pines that defies every attempt at explanation.

What’s odd about the trees? Well, look at the darn trunks, that’s what. IFLScience explains that the Crooked Forest, as it’s come to be known, consists of around 400 pine trees, all growing with that odd 90-degree bend in their trunks.

There are various theories as to how this happened (ranging from gravitational pull to a period of heavy snow bending the trees while they were still saplings, affecting their growth permanently), but nobody can say for sure.

14 Blood Falls, Antarctica: Get Out Of That Water, Dracula

As we’ve seen so far, then, there are still plenty of mysteries to go around. Smartypants scientists don’t have everything solved just yet, however many fancy books they’ve published.

With that said, though, there are some mysteries that we have been able to solve. One of these would be the case of Blood Falls in Antarctica, the alarming ruby-red waters that flow from the Taylor Glacier.

What’s happening here? It’s quite simple. “The deep red coloring is due to oxidized iron in brine saltwater,”Forbes reports, “the same process that gives iron a dark red color when it rusts. When the iron bearing saltwater comes into contact with oxygen the iron oxidizes and takes on a red coloring, in effect dying the water to a deep red color.”

13 The Super-Colony Of Ants That Covers Three Continents

Now, ants can be a pain. If you’re an avid picnicker like Yogi Bear, you’ll know this only too well. It just takes a couple of the little guys to ruin your whole afternoon.

One colony of Argentine ants is on a whole new level, though. As BBC reports, a single mega-colony has taken over much of the world. Distinct populations in the United States, Europe and Japan are believed to be one related community (some will not fight each other, unusually for this aggressive species).

They sport “a strikingly similar chemical profile of hydrocarbons on their cuticles,” suggesting that… well, as The Simpsons news reporter Kent Brockman once said, “I, for one, welcome our new insect overlords.”

12 The Wave, United States: New Wave? No, A Very, Very Old Wave

There are some places on Earth that just seem… otherworldly. If you were to show a picture of The Wave to somebody who had never heard of the place, they might well think they were looking at a landscape that high-tech NASA equipment had captured a shot of.

That’s not the case, though. The Wave is a stunning red sandstone formation found at the Vermilion Cliffs National Monument, along the northern border of Arizona/Utah. The rock formation is said to date back to the Jurassic period, and access is very strictly controlled. So much so, only small numbers of lucky lottery draw winners are granted access each day (for a day about four months in advance at that, in some cases).

11 The Danakil Depression, Ethiopia: a Whole New Kind Of Hostile Environment

I suppose some people are just hardier than others. I always marvel at the fact that my mailman wears shorts in all weathers, even the occasional blizzard. Here in England, where I live, we just don’t have the weather to support that sort of behaviour.

There are always limits, though. Even the best-prepared and foolhardiest of us can’t make some places work.

Ethiopia’s peculiar-looking Danakil Depression is one of these environments. I think National Geographic says it best:

“…a bizarre landscape worthy of the superlatives tossed at it. Hottest. Driest. Lowest. Weirdest. Though simmering hot springs, poisonous gases, crackling lava lakes, and salty mirages make the Danakil Depression seem like one of the most inhospitable places on Earth, even here, life has found a way. Multicolored hydrothermal vents are home to ecosystems that astrobiologists are now using as analog in the search for life beyond Earth.”

10 The Monolith Of Uluru, Australia: Where? How? When?

If there’s any one country that tends to baffle the rest of the world at times, it would have to be Australia. This noble, remote and beautiful island country boasts the kind of wildlife, customs and slang that outsiders sometimes find completely impenetrable.

The place is a real enigma. So, too, is one of its greatest tourist attractions: Uluru. Better known worldwide as Ayers Rock, this mysterious and sacred monolith has been puzzling visitors for centuries. It’s a single rock. How’s that even possible?

As of 2019, visitors will be banned from climbing Uluru, by the indigenous people who want to see their culture respected.

9 Thor’s Well, United States: It Hits Harder Than Mjölnir

If you travel to Thor’s Well in the U.S, I can’t promise that you’ll get to see Chris Hemsworth fighting various demonic creatures in a luxurious blonde wig and cape. I’m not going to strictly rule it out, either (you never know), but it’s unlikely.

I can promise a real natural spectacle to behold, though. Thor’s Well (or Spouting Horn) is a narrow opening in the rocks on the coast of Kauai, Hawaii. With the waves, water rushes into the opening and is expelled with great force. The pressure sometimes sends it fifty feet into the air! It’s pretty dang dangerous at close quarters, needless to say.

8 The Nasca Lines, Peru: Peculiar Peruvian Pieces

Crop circles are of the planet’s most enduring and high-profile mysteries. Believed to be the landing patterns of some intergalactic craft, and all kinds of other odd things along those lines, the revelation that some were hoaxes did little to quell them.

Peru’s Nasca lines are a similar phenomenon. More than a thousand of these giant geoglyphs have been found etched in the desert, some of which have been attributed to the Nasca people (of 200 to 700 AD). The Nasca lines as we know them are visible only from the air, and are remarkably intricate patterns drawn with a single line.

How did they do this? What do they really signify? There’s something truly intimidating about them.

7 Goblin Valley State Park, United States: Is There Life On Mars?

I’m not talking literally. After all, as we know from the movies, there is life on Mars. Matt Damon’s over there, growing crops using his fellow astronauts’ poop.

Instead, we’re talking about a truly unique valley in Utah, which boasts a landscape that’s often likened to what we’ve seen of the surface of Mars.

The Goblin Valley State Park is a truly intimidating place, the environment dotted with unnerving sandstorm formations. These spindly spires of rock are known as hoodoos, and the hoodoos of Goblin Valley are referred to by the locals as… well, goblins. What a sight this barren place is.

6 The Boiling River, Peru: When Myth And Fact Collide

As we saw with the Nasca lines, Peru is a country full of mysteries. Some artificial, some natural. Some we’ve got a good handle on, explanation-wise, and others we don’t. Let’s take a look at the mythical Boiling River of the Amazon.

This river is no myth, though. It’s real. Located in a secluded (very secluded) spot in the jungle, these waters reach temperatures of up to 200 degrees Fahrenheit, despite the fact that there is no volcano in the area (as is the case with similar rivers). Research is ongoing, and it’s believed that “a fault-led hydrothermal feature [is] causing the river to reach such temperatures.”

Alarming stuff.