In the year 1535, long before submarines or scuba gear, a remarkable feat of underwater exploration took place in Italy. Guglielmo de Lorena, a nobleman and engineer with a flair for invention, unveiled a mysterious device that allowed him to breathe underwater—an innovation centuries ahead of its time.
De Lorena, alongside his collaborator Francesco de Marchi, used this device to explore the depths of Lake Nemi, a volcanic crater lake southeast of Rome. Their goal: to investigate the remains of massive sunken Roman ships, believed to have once belonged to the infamous Emperor Caligula. What they found and how they found it would echo through the history of science and technology for generations.
The Invention: A Mysterious Diving Bell
The device de Lorena used was a type of diving bell—a submerged chamber that traps air, allowing a person to stay underwater far longer than would otherwise be possible. While the concept of a diving bell wasn’t entirely new—having been hinted at by Aristotle in the 4th century BC—de Lorena’s implementation was something else entirely.
De Marchi, who kept detailed accounts of their adventures, confirmed that the bell was not used for a mere glimpse beneath the surface. Instead, it enabled them to work on the lakebed—an achievement no one had reliably documented before. This was no fluke dive or fleeting inspection. It was a deliberate, sustained effort to investigate submerged ruins, marking the birth of practical underwater archaeology.
A Secret Mechanism Lost to Time
The most fascinating element of de Lorena’s invention was how it actually worked. While the general principle of a diving bell is straightforward—trap air in a chamber and submerge—it’s still unclear how de Lorena maintained a breathable atmosphere over extended periods. He was known to be protective of his methods and took the details of the mechanism to his grave. Historians and engineers alike continue to speculate: Did it include a system to refresh the air? Was it sealed in a special way? Or was there another trick lost to history?
The precise workings of this device remain one of the enduring mysteries in the history of science.
Ancient Concepts, Modern Breakthrough
Although de Lorena’s invention was not the first concept of a diving bell, it was the first to be documented by a firsthand witness during an actual underwater mission. Legends claim that even Alexander the Great descended into the sea in a glass barrel during the siege of Tyre in 332 BC—but these stories lack concrete evidence.
What de Lorena and de Marchi achieved at Lake Nemi, on the other hand, is not legend. It’s fact—recorded in writing, verified by scholars, and considered one of the foundational moments in underwater exploration.
A Legacy That Endures
The dive at Lake Nemi was more than just a bold experiment—it was a turning point. It demonstrated, for the first time in a documented way, that humans could venture beneath the water’s surface not only to observe but to investigate and work. It laid the groundwork for the development of modern diving technology, underwater archaeology, and even the dreams of oceanic exploration that followed in the centuries to come.
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Today, the spirit of curiosity that drove Guglielmo de Lorena and Francesco de Marchi lives on—in submarines that map the ocean floor, in robotic explorers scanning shipwrecks, and in archaeologists who still study the very same Roman vessels they once examined.
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What began as a mysterious descent beneath a quiet Italian lake turned into a historic moment that changed how we see the underwater world—and ourselves.
