Beneath a leafy park in the center of Montreal, an underground cavern has been enchanting visitors for decades. But within the spelunking community, many have speculated that there may be more to it than meets the eye. Then, two friends discover a small opening inside the wall of the cave – revealing a secret that’s been hiding since the last Ice Age.
As a boy in the 1960s Daniel Caron spent his days exploring the far reaches of Saint-Leonard Cavern, a cave that stretches under the Montreal neighborhood of the same name. And despite running afoul of the local authorities from time to time as a result of his night-time excursions there with his buddies, he developed a lifelong love of the underground world. Five decades later, he took his hobby to the next level, revealing something incredible lurking beneath the city.
Along with Luc Le Blanc, a friend and fellow caver, Caron spent three years following a hunch: that there was something beyond the wall of Saint-Leonard Cavern. And when the two men finally broke through to the other side, their suspicions were confirmed. There, concealed behind a solid slab of limestone, was what they had suspected might have been lying hidden from view.
But what did Caron and Le Blanc find down in the darkness beneath Montreal? Left behind when the last Ice Age ended some 10,000 years ago, it’s a startling relic from a time when woolly mammoths roamed the Canadian wilds. And now, for the first time in millennia, a select group of visitors have been invited to take a peek.
Today, it might seem unlikely that this city of 1.78 million people in the province of Quebec could have held on to a secret for thousands of years. But of course, Montreal hasn’t always been the bustling metropolitan hub that you see today. In fact, the region was originally home to Hochelaga, a small fortified settlement built by First Nations people.
Then, in the 16th century the French colonists arrived, turning Hochelaga first into a Christian mission and then an outpost whose economic lifeblood was the fur trade. But it was under the British, who conquered the region then known as New France in 1763, that Montreal really began to thrive. Located on the banks of the Saint Lawrence River, the settlement soon blossomed into a manufacturing and transport hub.
By the time that Canada was unified in 1867 Montreal had become the biggest city in the entire country. And it remained that way for more than a century, before it was eventually surpassed by Toronto. Even today, it is the second-most-populated metropolitan area in Canada, home to more people than the capital, Ottawa, which lies some 120 miles to the west.
Set largely on an island in the southern tip of Quebec, Montreal has long been known as one of the most culturally varied places in North America. And every year, millions of tourists visit the city, drawn by attractions such as the Botanical Garden and the annual Jazz Festival. It even plays host to motor racing in the shape of Formula One’s Canadian Grand Prix. But until now, they have all remained totally unaware of the secret hiding beneath their feet.
As Montreal grew, so too did the nearby settlement of Saint-Leonard. And eventually in 2002 it was swallowed up by the city, becoming a borough of the extended metropolitan area. Home to a large number of Italian-Canadians, whose families moved there after World War II, the area has plenty going on above ground. But few could have imagined what was lurking down below.
In 1812 a vast cavern stretching more than 100 feet across was discovered beneath Saint-Leonard’s Pie XII Park. But any early would-be cavers would not have had much chance to explore it. Within 25 years, conflict had broken out across the region once more as the people of what is now southern Quebec rebelled against their government.
Beneath the streets of Montreal, the cave was put to good use, serving as both an arsenal and a hiding place for the rebels. Then, in 1838 the military succeeded in suppressing the opposition, putting an end to the conflict known as the Patriots’ War. And down in Saint-Leonard Cavern, things fell silent once more.
For decades, the cave remained little more than a footnote in the history of Montreal, overshadowed by the city’s more cosmopolitan attractions. But for local children, this dark and sinister underground chamber must have held its own secretive appeal. Certainly, that was the case for Caron, who grew up in the nearby neighborhood of Saint-Michel.
In fact, Saint-Leonard Cavern proved to be an early inspiration for Caron, who would grow up passionate about spelunking, or exploring underground. During his teenage years, he and his friends made a number of forays into the area – despite the fact that it was then off-limits to the public. And although the authorities tried to prevent them, they succeeded in accessing the cave on at least one occasion.
But it may have been more than just curiosity that spurred a young Caron to explore the underground network beneath Pie XII Park. After all, there were many in the Montreal caving community who believed that the cavern discovered in 1812 was just the beginning. And that something else, hidden for millennia, was still lurking down in the dark.
It would be several decades, however, before Caron would discover the truth. And in the meantime, Saint-Leonard Cavern went through a number of changes. First, in 1978 members of the Quebec Speleological Society, or SQS, decided to open the cave to experts, allowing study of its unique geological features.
In the early years of the following decade Saint-Leonard – still then a city in its own right – realized the value of the cave as a potential tourist attraction. Rather than fight to keep curious visitors out, officials reasoned, they could simply create an access point and allow admission on their own terms.
In order to develop their new tourist attraction, the city constructed a door and a metal gate at the entrance to the cave. With this opening secured, they hoped to stop trespassers such as Caron and his friends from getting inside. Meanwhile, a set of steps was built, making a trip into the heart of the cavern a much less challenging undertaking.
Thanks to this new ease of access, Saint-Leonard Cavern soon became a popular destination. In fact, it’s believed that as many as 70,000 visitors have passed through its doors since it opened in 1982. But all that time, rumors have continued to swirl that there is more to the cave than meets the eye.
Meanwhile, Caron and his friend Le Blanc had grown up and joined the SQS, exploring Quebec’s caves in a more official capacity. But their developing knowledge of the region’s underground networks did little to dispel their own hunches about Saint-Leonard Cavern. And eventually, they decided to get to the bottom of things once and for all.
That year, the two cavers kitted themselves out with everything they needed to explore the furthest reaches of the cave. For Le Blanc, that meant a piece of equipment that uses radio waves to reveal cavities or spaces behind solid rock. But for Caron, it signalled a decidedly more old-fashioned approach.
According to British newspaper The Guardian, Caron used the ancient practise of dowsing to search for anomalies in the depths of Saint-Leonard Cavern. Believed by some to have originated in 16th-century Germany, this bizarre method involves using rods to locate resources such as water or metal within the landscape.
Today, dowsing is considered a pseudoscience by most people. But despite this, it is still used in a professional context in places such as the United Kingdom, particularly by workers keen to locate mains water pipes. And so, it was perhaps not overly unusual that Caron decided to use the technique inside Saint-Leonard Cavern.
At first, Caron and Le Blanc’s efforts revealed little about the secrets lurking beyond the cave. But then in 2015 they spotted a small gap in one of the rock walls – just big enough to slip a tiny camera inside. With the help of François Gelinas, a fellow caver, they decided to take a closer look.
Viewing the camera footage, Caron and Le Blanc realized that their hunch had been right. There was something hiding beyond the cavern. But there was a problem: whatever it was, it was concealed behind a thick wall of limestone. And if they wanted to reach it, they would need to use industrial drilling equipment to break through.
Ultimately, it would be almost two years before the cavers could take their investigation to the next stage. In October 2017 they were able to dislodge a section of rock and drill into the cavern wall. Speaking to the Canadian television network CBC that year, Le Blanc explained, “We started digging in a decomposed layer of limestone that was much softer… We managed to open a window.”
Squeezing their upper bodies through the opening, Caron and Le Blanc saw something incredible: a huge, open chamber on the other side of the rock wall. Speaking to local newspaper the Montreal Gazette in 2017 Caron recalled, “It was vast. We started yelling, ‘Yes! We did It! We did it!’”
The following day, the two men returned to Saint-Leonard Cavern, determined to make it through into the newly-discovered chamber. But after enlarging the opening, they realized that there was too much of a drop on the other side. Eventually, they acquired a ladder and were able to lower themselves down into the unknown.
Finally climbing down the ladder and shining their torches into the darkness, the cavers found themselves in a space some 20 feet tall by 10 feet wide. Speaking to the Montreal Gazette, Caron confirmed his sense of achievement at the discovery. He said, “In the life of a spelunker, something like this happens once.”
In fact, the cave discovered by Caron and Le Blanc is actually far bigger than the well-known Saint-Leonard Cavern. And from the main chamber, it branches off in several directions. In some places, the way is blocked by water, meaning that its furthest reaches have yet to be explored.
At one point, Caron and Le Blanc jumped in the water and explored the cave by swimming through its submerged branches. And if that wasn’t enough, they even brought a small boat through the entrance and inflated it once inside the grotto. But even with these measures, they were unable to cover the entirety of a network that they believe stretches some 700 feet.
In an interview with National Geographic magazine, Caron explained that the water flows into the cave from an aquifer located far below the streets of Montreal. And an aquifer, if you didn’t know, is just a fancy name for underground rock which retains water in the same manner as a sponge. In some places, pools in the cavern are as much as 16 feet deep. Speaking to CBC, Le Blanc added, “It just keeps going. We haven’t reached the end yet.”
While the keen explorers might not have mapped every inch of their discovery just yet, what they have uncovered so far is impressive. Describing the cavern to National Geographic, Le Blanc said, “The walls are perfectly smooth and the ceiling is perfectly horizontal.” But in several places, the even surfaces are broken up by stalactites and stalagmites.
These mineral formations, which grow down from the ceiling and up from the ground, respectively, have been found in caves around the world. And according to the SQS, they typically grow at a rate of about 0.4 inches every thousand years. From pictures of Caron and Le Blanc’s discovery, then, it seems as if this cavern has been around for a very long time.
So how exactly was this hidden chamber beneath Montreal formed? According to experts, it’s not actually all that common to find caves located this far north. Speaking to National Geographic, Le Blanc explained that caverns are typically formed when water eats away at the rock over a number of years.
But in Quebec, where temperatures have been known to drop as low as -31°F, the water has lower levels of acidity. And so, caverns tend to form much more slowly, making them rarer generally at these latitudes. Happily for cave fans such as Caron and Le Blanc, though, another geological process set in motion thousands of years ago also brings its influence to bear.
Today, experts believe that Saint-Leonard Cavern took shape via a process sometimes dubbed glacial tectonism. In layman’s terms, this refers to geological features that were carved out of the Earth by melting and retreating ice. And like its more famous neighbor, the cave discovered by Caron and Le Blanc was likely formed in the same way.
Some 15,000 years ago, when experts believe both caves were formed, Canada – along with the rest of the world – was in the grip of the last Ice Age. And as a massive glacier formed where Montreal now stands, the pressure caused the rocks beneath to crack. Fast-forward to the 21st century, and this fissure has become not one but two jaw-dropping caverns.
According to Le Blanc, the traces of this process can still be seen today. Speaking to National Geographic, he explained, “You have evidence of where you have knobs on one side that fit perfectly into a hole on the [opposite] wall.” In fact, he claimed, the rock faces slot together like pieces of a jigsaw.
In a slightly ironic twist, given Caron’s past exploits, news of the discovery of the new cavern was postponed until the location could be secured. Presumably, the Montreal authorities were not keen on any amateur explorers finding their way into the network. That said, there have been a few lucky visitors to the cave, including reporters who were given a tour in December 2017.
Eventually, it’s hoped that this new chamber, like Saint-Leonard Cavern, will be open to the public for tours. But first, experts hope to study and document its fascinating geology. In an interview with the Montreal Gazette, local councillor David Perri explained, “The specialists tell us this type of cave is very unusual, if not unique in the world. We want to maintain it because it is our heritage, but also because it has scientific value in terms of the way it is shaped and how it was made.”