The world is full of amazing sights, sounds and mysteries.
While some are spectacular examples of what Mother Nature is capable of, others are just plain weird.
Through the centuries people have wondered what caused them, giving rise to tales of UFOs, genies and entrances to hell.
In some instances, the mysteries behind these weird wonders remain unsolved.
But others can be explained by phenomenons that have captivated some of the finest scientific minds on the planet.
Here we examine a handful of Planet Earth’s strangest sites and examine everything top boffins have actually been able to tell us about them.
Well of Hell, Yemen
Officially called the Well of Barhout, this sinkhole in Yemen, which measures 100ft across and 357ft deep, has long been said to be the home of devils and genies, or even the gateway to the underworld.
Despite having sent a man to the moon and explored the depths of the oceans, only this month did cavers finally reach the bottom of the hole, battling darkness, low oxygen levels and noxious fumes.
They didn’t find any genies but only some snakes and dead animals.
Crooked Forest, Poland
In a quiet forest in western Poland are dozens of strangely identical crooked trees.
For years there have been various theories on what caused them to grow this way. Some say snowfalls bent the trunks or some sort of weird horizontal gravitational pull, maybe caused by a UFO landing.
The answer is more simple, but tragic. It is believed they were planted and then shaped while growing that way by foresters for ship building.
Sadly, the entire area was utterly devastated in World War Two, the nearby town razed to the ground and those who have the answers did not survive to tell them.
Fairy Circles, Namibia
In the Namibian desert are thousands of weird circles on the desert floor.
Scientists have pondered for decades what caused them, then they thought they had it.
They believed termites under the ground were clearing the vegetation above so rare rainfall would not be gobbled up by the plants. Each colony had its own little fairy circle.
Then other scientists pointed out a similar phenomena exists in Australia in areas where where there are no termites. Maybe it is fairies after all.
Door to Hell, Turkmenistan
In the middle of the vast, empty Turkmenistan desert is a terrifying sight – a gaping burning pit, 225ft wide and a 100ft deep. It also roars like a jet engine and has been burning for 40 years.
There is no mystery to what has caused it ,though.
When a drilling rig collapsed in the 70s, Soviet miners stated a fire to burn away noxious gas. This lit the underground gas and ever since it has burned like the world’s biggest gas ring.
Great Blue Hole, Belize
This giant sinkhole near Belize is around 400ft deep and 1,000ft across.
It formed when a cave was flooded and is a popular scuba diving site.
In 2018, two submarines dived in to make a 3D map of the interior and discovered two dead divers at the bottom.
The Discovery Channel once ranked it at number one in its list of “The 10 Most Amazing Places on Earth”.
Eternal Flame, US
In New York’s Chestnut Ridge Park is a waterfall, and behind it burns an eternal flame.
But before anyone gets too misty-eyed about it, it is actually caused by leaking methane gas and often goes out, but can easily be restarted by a lighter.
It was not, to our knowledge the inspiration for The Bangles’ number one hit, which was later covered by Atomic Kitten.
Richat Structure, Mauritania
Known as The Eye of the Sahara, this 30 mile wide swirl in Mauritania, which from above looks like a bullseye, is so big it can clearly be seen from space.
Predating life on earth, scientists first thought it was caused by an asteroid but now say it was a volcanic dome which over millions of years has eroded, exposing the onion like layers of rock.
Kawah Ijen, Indonesia
Visitors to this beautiful lake high in East java, Indonesia, might be tempted to take a dip in its attractive, cooling waters.
But best not. The lake has very high levels of sulphuric acid caused by nearby volcanoes. These are sometimes so high in the surrounding area they ignite to form shooting blue flames.