In the geological past, Antarctica had a different climate, and some experts believe that lakes have been trapped there for millions of years.
These ancient subterranean bodies of water are known as ghost lakes. What on Earth is investigating.
The world's strangest places
The world's strangest places
Visit the mysterious island of Socotra and you'd be forgiven for thinking you were on another planet. Part of a group of islands off the African coast, this place teems with more than 800 rare species of flora and fauna, many of which can't be found anywhere else on earth.
Want to go there? The best time for wildlife enthusiasts to visit is between January and May. Flights run from Sana'a Airport, the capital of Yemen. There is a growing offering of tourist accommodation. Visit Socotra Eco Tours for more.
This incredible rock formation is the result of hundreds of millions of years of erosion: the stripes are caused by leaking minerals in the rock.
Want to go there? Simple! You just need to drive four hours east from Perth...
This huge hole in the sea off the coast of Belize is so large and deeply blue that it's visible from space. It's believed to have formed after the Ice Age, when ice melted into the sea, covering a giant collection of caves. It's a popular spot with divers as it brims with aquatic life.
Want to go there? Take a 75-minute ferry trip from Belize city or a 20-minute flight to San Pedro.
These ancient rock formations on the Otago coast of New Zealand are believed to date back more than 60 million years. The largest boulders weigh seven tonnes. Mauri ledgend tells that the boulders are remains of eel baskets, while locals call them "giants' gobstoppers".
Want to go there? Have a look at our guide to New Zealand for more information.
Nestled in the heart of Cappadocia in central Antolia, this eerie national park is composed of strange rocks shaped over centuries out of eroded volcanic stone.
Want to go there? The park can be reached on foot from Goreme village, where there is a plethora of hotels and pensions. Best time to visit is March til November.
These 'elephants' are part of train of gigantic pink granite boulders perched on a hill These curious geologic formations were formed 1.5billion years ago out of magma being pushed to the surface.
I want to go there! Drive or book a coach tour from Las Vegas to the Valley of Fire.
Fancy an egg cooked on 'Sulfur Mountain'? The vents on this volcano are permanently steaming and smoking, and vendors sell eggs that have been cooked by the natural heat.
Want to go there? Iozan is part of Akan National Park, just outside the hot spring resort of Kawayu Onsen. Main gateways to the park are Kitami and Bihoro in the north, and Kushriro in the south.
This fairytale-like cascade of thermal spring waters is a unique natural site considered by many to have healing properties (the waters have been used since Roman times). The springs are laden with calcerous salts which have created plateaus, stalactites and basins to form Pummukkale, which literally means "Cotton Castle".
Want to go there? The springs are about 30km from Bodrum by car, or you can book a day trip from the city. If you want to stay, there are limited options, but the nearby town of Denizli is a safer bet for accommodation.
Green Sand Beach, or Papakolea, is one of only two green sand beaches in the world. Sitting on the sotuthern tip of Hawaii's Big Island, the sand is a distinctive olive green colour caused by a now extinct volcano.
Want to go there? Green Sand Beach is pretty isolated - you'll need to take a three hour drive from the nearest resort along the Kohola Coast.
Huge craters, steaming ground, sinister rock formations, hot water springs and lime green water: the Devil's Bath has to be seen to be believed. Wai-O-Tapu Thermal Wonderland, Rotorua is New Zealand's most diverse geothermal area.
Want to go there? Rotorua is a three-hour drive from Auckland and is well served by hotels and visitor centres. Visit RotoruaNZ for more.
Thousands of delicately carved spires rise in brilliant colour from the rock amphitheatres, created by millions of years of wind, water and geologic mayhem.
Want to go there? Take a day tour from Las Vegas or spend some quality time and stay overnight in one of the many lodges nearby.
What makes these volcanic lakes so special? Well, they actually change colour from green to blue, red and black. The locals believe that The Lake of Old People, Lake of Young Men and Maidens and The Enchanted Lake are the spiritual resting place of their ancestors and change colour depending on the moods of the spirits. Don't be tempted to get too c lose though, in 1995 a Dutch tourist fell into one of the lakes and his body was never recovered.
Want to visit here? Kelimutu is in the centre of Flores and tourists start their trek from the small village of Moni, nine miles from the lakes.
Mount Roraima has sheer, plummeting, 400-meter high cliffs and is bordered by three different countries - Venezuela, Brazil and Guyana. It sits in Guyana's Highland Range, some of the oldest geological formations known to man and is home to its own ecosystem, the world's highest waterfalls and unique wildlife like the carnivorous pitcher plant.
Want to visit here? The cliff walls can only be tackled by experienced climbers but there is a hiking path that occurs naturally in the mountainside. See explore.co.uk for holiday ideas.
An hour from Senegal's capital is Lake Retba, a vividly pink lake surrounded by sand dunes. The lake has a salt content similar to the Dead Sea and its distinctive colour comes from the Dunaliella salina algae. Not much lives in the lake and locals use it to mine salt and promote tourism in the area.
When to go: The lake is pinkest during the dry season from November to June.
Deweze, or The Door to Hell, as it is more commonly known, is found in the middle of the Karakum Desert. It was discovered in 1971 when Soviet geologists drilled into a cavern filled with natural gas. The ground collapsed revealing a huge hole filled with poisonous gases. To avoid the discharge they decided to try and burn the gasses away and it's still burning today.