While a few of these natural wonders formed as a result of meteors raining down through our atmosphere, many more were skillfully crafted by the volcanic hands of our own Mother Earth. From the active hot spots of Iceland and Indonesia to the now-extinct volcanic relics of millennia long past, these dramatic depressions provide an invaluable peek into the geological history of our planet.
Crater Lake, Mount Mazama, Oregon
Arguably the most iconic caldera lake in the United States, this natural wonder is the main attraction in the appropriately titled Crater Lake National Park. The 2,148-foot-deep lake was formed around 5,667 B.C. after the eruption and collapse of Mount Mazama.
Before its destruction, the stratovolcano was regarded by the local Klamath Native American tribe to be the god of the underworld, known as Llao. The collapse of the mountain was witnessed by the Klamaths, who recorded it as a great battle between Llao and their sky god, Skell.
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Blue Fire Crater, Kawah Ijen Volcano, Indonesia
Don't let the beautiful mint green hue of this crater lake deceive you. The picturesque Kawah Ijen is actually filled with sulphuric acid, and it lays claims to being the largest highly acidic lake on Earth, according to the Smithsonian's Global Volcanism Program. With all that sulphur washing up on the shore, it also the home of an active sulphur mine. It's common to see miners hand-carrying large baskets full of bright yellow chunks of solid sulphur uphill from the lake's shore.
The crater has become a popular tourist destination in recent years, thanks in part to global publicity generated around its famous blue fire, which is the result of sulphuric gas igniting as it escapes cracks in the ground.
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Kaali Lake, Saaremaa, Estonia
Some people might call this sublime natural wonder a pond rather than a lake, but regardless of semantics, it's easy to understand why this tree-sheltered circular depression would play such a huge part in the local Estonian mythology. The lake, along with its eight sibling craters, are the result of a violent meteor impact that is generally agreed to have occurred between 4,000 and 7,600 years ago. The energy of the impact is believed to been brutal, and has even been compared to the 1945 atomic bombing of Hiroshima.
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Mount Katmai, Alaska
This remote crater lake situated in the caldera of a 6,716-foot-high stratovolcano is found in southern Alaska's Katmai National Park and Preserve. Measuring about 6.3 miles in diameter, the Mount Katmai caldera was formed in 1912 after the first-time eruption of the nearby Novarupta volcano.
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Rano Kau, Easter Island
While most people associate Easter Island with its iconic moai head statues, there are plenty other things to explore on the island. One such site is Rano Kau, an extinct volcano that is home to a crater lake that lays claim to being one of the only natural bodies of fresh water found on the island. The world heritage site is contained within the Rapa Nui National Park alongside the ruins of an ancient ceremonial village known as Orongo.
One interesting yet depressing fact to know is that the last wild toromiro tree (a species endemic to the island that was almost completely eradicated by the 17th century) was chopped down on the crater's inner slope in 1960.
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Okama Lake, Mount Zao, Honshū, Japan
The bright turquoise hue seen in the photo above is just one of many colors the water takes on at Okama Lake, which is also known as the "Five Color Pond." Formed by a complex volcanic eruption in the 18th century, this natural treasure of Japan measures about 1,200 feet in diameter and 200 feet in depth.
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Lake Tritriva, Vàkinankàratra, Madagascar
Located 30 minutes outside of the city of Antsirabe, this small yet breathtaking volcanic lake is surrounded by steep cliff walls of gneiss rock. While it's possible to swim in the lake, the water is cold and very, very deep — over 160 meters deep, to be exact. To understand the scale of that measurement, check out this video of a man bungee jumping off a 160-meter-high bridge.
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Segara Anak, Mount Rinjani, Lombok, Indonesia
This beautiful crescent-shaped lake is what remains after a violent eruption destroyed the mountain in 1257 A.D. The eruption is estimated to have measured a whopping 7 on the Volcanic Explosivity Index, meaning it would have been one the strongest volcanic eruptions to occur in the last few millenia. Some scientists speculate that the enormous eruption might have been one of the triggers of the Little Ice Age, a period of cool climate cooling lasting between the 16th and 19th centuries.
Today, Segara Anak, which means "child of the sea," is a popular destination for camping, swimming and religious pilgrimages.
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Kerid, Grímsnes, Iceland
Iceland is full of surreal, otherworldly sites, and this beautiful crater in the country's Western Volcanic Zone is definitely one you shouldn't miss. Known as "Kerið" in Icelandic, this shallow, mineral-rich lake is surrounded by steep red volcanic rock walls sparsely covered in moss and other vegetation. While the caldera itself is about 55 meters deep, the actual water depth fluctuates between 7-14 meters depending on rainfall amounts.
The best way to see Kerid is to travel along a popular tourist route called the Golden Circle, a 300-kilometer loop that covers the most amazing natural sites in southern Iceland.
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Heaven Lake, Baekdu Mountain, China and North Korea
Situated on the border between China and North Korea, this pristine, precipitation-fed lake was created around 969 A.D. when a major eruption formed a caldera atop Baekdu Mountain.
There are many legends regarding the lake that persist to this day. For one, the late Kim Jong-il claimed that he was born on the mountain near the lake. Upon his death in December 2011, the North Korean news media reported that as he died, the lake ice cracked "so loud, it seemed to shake the Heavens and the Earth." Additionally, the lake is rumored to be the home of the Tianchi Monster, which some locals have described as having a human-like head, an unusually long neck and smooth, grey skin.
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Kelimutu, Flores, Indonesia
There are three volcanic lakes found on Kelimutu — the image above shows Tiwu Ko'o Fai Nuwa Muri (Lake of Young Men and Maidens) and Tiwu Ata Polo (Bewitched Lake), which are separated by a single crater wall. The other is called Tiwu Ata Bupu (Lake of Old People)
What's extra interesting about this lake trio is that they are different colors despite being on the crest of the same volcano. The color changes are attributed to chemical reactions between lake minerals and changing volcanic gases.
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Öskjuvatn Lake, Víti crater, Askja, Iceland
Does this environment looks like something out of a science-fiction movie? If so, you're not the only one to think that! NASA once trained its astronauts in this remote, otherworldly landscape to prepare them for the lunar missions of the Apollo space program.
Today, the mineral-rich, sulphurous waters of Öskjuvatn are experiencing a warming period. While in the past the lake's surface generally stayed frozen until June or July, it was discovered in April 2012 that the lake's ice had already melted as a result of increased geothermal activity.
While it's possible to swim in the lake, carbon dioxide can accumulate just above the surface of the water, creating a dangerous situation for swimmers.
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Pingualuit Crater, Ungava Peninsula, Quebec, Canada
Formerly known as the Chubb Crater, Pingualuit is a relatively young impact crater, geologically speaking. The meteor impact that formed it is estimated to have occurred about 1.4 million years ago (give or take 100,000 years), which puts it firmly in the Pleistocene epoch.
Surrounded by a desolate, tundra landscape, the lake is one of the deepest lakes in North America, as well as one of the purest and clearest freshwater lakes in the world. A secchi disc, an object used to measure water transparency, can be seen as far down as 35 meters below the surface.
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Quilotoa, Andes mountains, Ecuador
Formed after a catastrophic volcanic eruption about 800 years ago, this watery caldera is well on its way to becoming a prime tourist destination. The turquoise lake at the center of the crater is well worth the drive and hike, though due to the acidity of the lake, a celebratory swim would be out of the question. Regardless, the view from along the rim is truly a sight to behold!
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Lonar Lake, Buldhana district, Maharashtra, India
While it doesn't look like two lakes, Lonar Lake sort of is. Both saline and alkaline in nature, Lonar Lake is home variety of plant and animal life. Indeed, the area is so rich in wildlife that there were efforts to have the lake declared a protected wetland in 1999. Indeed, between its dual nature and the fact that it's an ideal spot for scientists to study impact craters similar to those on Mars and the moon, Lonar Lake is a mysterious but marvelous crater lake.
This story has been updated with new information since it was first published in August 2014.