1. Guaíra Falls Prior to 1982, visitors to the Upper Paraná River along the Brazil-Paraguay border came across an awe-inspiring sight: a series of at least 18 waterfalls, known as Guaíra Falls. The water plunged a total of 375 feet, and it’s said the falls thundered so loudly, people could hear them from 20 miles away. Guaíra Falls are believed to have been the most powerful waterfall in the world in terms of volume.

But their might was no match for the Paraguayan and Brazilian governments. The two countries began constructing the Itaipú Dam—part of a massive power plant—in the 1970s. After being completed in 1982, the dam created a reservoir so large it completely submerged the popular waterfall.

Hi, I’m Erin McCarthy, editor-in-chief of mentalfloss.com. Guaíra Falls are just the first of several places that no longer exist we’ll be exploring today. Let's get started.

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2. The Pink and White Terraces are another natural tourist attraction we’ve lost. New Zealand was once home to what was widely called the Eighth Wonder of the World. Geothermal springs sent water full of silica flowing downward near Lake Rotomahana, on the country’s North Island. As the minerals hardened, they formed terraces brimming with warm water.

The Māori had long valued the Pink and White Terraces; they viewed them as taonga, or a treasure. After Europeans colonized New Zealand, people came from around the world to admire their beauty and soak in the pools, which were said to have healing powers. The site was a great source of revenue for the local Māori, who worked as guides. Until 1886, that is.

On June 10 of that year, Mount Tarawera erupted. The Pink and White Terraces—along with the nearby village of Te Wairoa—vanished. The explosion killed more than 100 people and sent the storied world wonder to the bottom of a crater, which later flooded to become an even larger Lake Rotomahana.

3. There was once an island called Strand off the northwestern coast of what’s now Northern Germany. In January of 1362, a cyclone known as the Grote Mandrenke, or “Great Drowning of Men,” caused a storm surge that wiped parts of the island off the map. With them went the medieval town of Rungholt.

For centuries after Rungholt’s disappearance, people spoke of it as if it were a mythical lost city; but it was potentially uncovered in 2023. What was left of Strand, meanwhile, remained above water for another 300 years. In 1634, another huge storm surge flooded the area, permanently splitting Strand into the smaller islands of Nordstrand, Pellworm and Nordstrandischmoor.

4. People aren’t the only ones who suffer when islands disappear. After a 2018 hurricane, East Island—part of the French Frigate Shoals of the Hawaiian Islands—was swallowed by the sea. Its disappearance was a major bummer for Hawaiian monk seals and Hawaiian green sea turtles. Roughly 30 percent of all Hawaiian monk seals were born on East Island and a large percentage of the Hawaiian green sea turtles nested there, so losing it was a devastating blow for the already endangered species.

Research has shown that they’ve likely turned to other French Frigate Shoal islands, which are just as vulnerable to rising sea levels. And some are still on East Island, which has sort of rebuilt itself after the hurricane, but is still only half the size it was before.

5. Losing valuable land to the sea is nothing new. Take Doggerland, for example. The large swath of land once connected Great Britain to continental Europe. Long-extinct animals like cave lions, saber-toothed cats, mammoths, and cave hyenas roamed the area—as did modern humans and our ancestors. But as the planet continued to warm in the years following the last glacial maximum, the once-hospitable Doggerland began to take on water.

Then, about 8200 years ago, a massive flood from a glacial lake in North America and a tsunami caused by a landslide off the coast of Norway sealed its submarine fate. The drowned remnants of what’s now been dubbed “The Atlantis of the North Sea” remained hidden beneath the surface until the early 1930s. That’s when a barbed antler point potentially used as a spear was discovered within some peat a fishing trawler accidentally caught. That artifact clued 20th-century archaeologists into Doggerland’s existence. Archaeologists, community scientists, and fishermen continue to dredge up old objects various hunter-gatherers left behind.

6. We can’t talk about lost landmasses without mentioning the Bering Land Bridge. The area linked North America to Asia and was part of Beringia, which is wedged between Russia’s Lena River and Canada’s Mackenzie River. It’s believed the land bridge formed around 35,700 years ago, when the sea levels lowered during the Pleistocene Ice Age’s last glacial maximum, creating a passage between the two continents.

According to a popular theory, humans came to the Americas via the Bering Land Bridge. Some researchers believe people lived on the 600-mile-wide stretch of land, where they would have hunted elk and small mammals and used wood fires to burn their bones. As with Doggerland, when sea levels rose at the end of the Ice Age, most of the Bering Land Bridge eventually became submerged, severing the passageway between the two continents.

7. The Sahara desert is famously hot and dry. But the part of Africa it now covers wasn’t always so parched. Rivers and lakes dotted the land around between 130,000 and 100,000 years ago. The Irharhar was just one of the rivers that once flowed there, and it linked two relatively humid climates: a monsoon-riddled region in the south, and the Mediterranean to the north. The area around it would have been lush with flora and fauna.

According to one 2013 study, the Irharhar may have had a major effect on early human migration. The study’s authors suggest that Northern Africa’s lost river systems could have served as a migration corridor that allowed our ancestors to leave the continent. Today, though, the vanished river remains buried beneath sand dunes.

8. The end of the Ice Age caused several devastating floods, many of which left lasting marks on the Earth. Dry Falls in Washington is just one piece of evidence of their power. Don’t be fooled by its name—the cliffs may now be dry, but they once formed a waterfall said to be five times wider than Niagara Falls, where the water’s flow was 10 times more powerful than all of the world’s rivers combined. The waterfall formed after ice sheets cut off a river, basically creating a massive ice dam. The water kept piling up behind the ice until it broke through and sent enormous floods hurtling across the northwest. There was more than just one of these catastrophic events: Geologists believe several of these floods battered the area over the span of a few thousand years. They shaped the landscape in incredible ways.

But after the ice dams melted and the glaciers retreated, those huge glacial lakes stopped flooding and the rivers returned to their normal courses, putting an end to Dry Falls. What was once the planet’s mightiest waterfall now resembles an ordinary cliff.

9. For centuries, an old man’s face loomed over New Hampshire, peering out from the side of Cannon Mountain. The Indigenous Abenaki called him “Stone Face,” while the white settlers referred to him as the “Old Man of the Mountain.” Except it wasn’t an old man at all: It was a rock. The “Old Man of the Mountain,” like Dry Falls, was shaped by the last Ice Age. Erosion caused by the freeze and thaw cycles the warming climate created carved an astonishingly human-like shape into the rock.

The Old Man of the Mountain became a beloved symbol of New Hampshire, but the years were not kind to him: First, his forehead began to crack. Workers had to make extensive repairs on the rocks throughout the 20th century as he continued to crumble. The iconic Old Man of the Mountain fully collapsed in the early hours of May 3, 2003. There’s now a memorial viewing plaza in the spot he once loomed over.

10. If you think the Himalayas are impressive, you would’ve been blown away by Earth’s ancient supermountains. One range, called the Nuna Supermountains, were as tall as the Himalayas, but were estimated to be about 5000 miles long. (The Himalayas, in comparison, are a mere 1500 miles long.) The Nuna Supermountains stretched across an entire supercontinent and formed roughly 2 billion years ago. Their disappearance was, in a way, our gain: According to a 2022 study published in Earth and Planetary Science Letters, as the mountains eroded, they sent a deluge of phosphorus, iron, and other nutrients into the ocean, and helped up the amount of oxygen in the atmosphere. This was a boon for evolution. The study suggests that this influx of key nutrients boosted biological cycles that led to the evolution of Eukaryotic cells—the very cells that would go on to evolve into lifeforms like animals, plants, and fungi.

That's it for this week's episode of The List Show. Thanks for watching and we'll see 'ya next time.