The Incredible Diving Bell the Romans Kept a Secret for 500 Years

by Owen James Burke


The Romans managed to keep an incredible scientific secret until now. Image via Ancient Origins

In July of 1535, an Italian inventor by the name of Guglielmo de Lorena and his partner Francesco de Marchi began surveying a pair of sunken barges on a lake which once belonged to 1st century A.D. Roman emperor Caligula. The two men did not let on how they were accomplishing their feat, and until now, no one had proposed any clear hypothesis as to how the they managed to descend to the bottom of the 108-foot deep lake and remain there long enough to gather the information and artifacts with which they returned.

In light of a recent article featured in The International Journal for the History of Engineering & Technology entitled “Guglielmo’s Secret: The Enigma of the First Diving Bell Used in underwater Archaeology,” researcher Dr. Joseph Eliav credits Lorena with developing the first one-man diving bell designed specifically for archaeological purposes. Suggesting that the 16th century Italian had designed a diving bell that was, at the time, by far the most advanced of any diving apparatus, Dr. Eliav puts forth the notion that Lorena developed the first air-exchange system which allowed divers to spend not just precious moments but hours underwater at a time.


Above: A 16th century Islamic depiction of Alexander the Great (356-323 B.C.) in his glass diving bell. Public Domain.

There are accounts of underwater breathing devices for the sake of hunting and military purposes that date back much earlier to Alexander the Great who apparently employed a diving bell during the siege of Tyre. And just decades before Lorena and Marchi’s mysterious accomplishment, Leonardo da Vinci had written about various underwater diving apparatuses, namely helmets with long snorkels.


There’s no way that strap through the groin could have been very much fun, but it looks to be what would have kept the whole rig intact. Image credit: The Newcomen Society for the Study of the History of Engineering & Technology 2015

The air exchange system above allowed the diving chamber, or bell, to maintain pressure while still refreshing the diver’s air supply so they didn’t suffocate. Apparently, as one might suppose, the diver wore no protective layering, and would undergo submersion in nothing but bare flesh. A shallow-water dive might not have been so uncomfortable, but the diver was dry from the chest up in what might have been described as a sauna, while their lower half would have been near frozen at depth–surely this must have been a bewildering sensation.


This was one of two shipwrecks in Lake Nemi said to have belonged to Roman emperor Caligula, recovered in 1929. To get an idea of the sheer mass of these vessels, look at the people in the foreground for scale. The ships were said to have been wildly ornate with mosaic floors, heating, and plumbing for baths, inspired by the decadent rulers of the Hellenistic period. Sadly, both barges were both destroyed by a fire in 1944. Image: Wikimedia Commons

19 miles south of Rome, Lake Nemi has a surface area of less than three-quarters of a square mile, and during Caligula’s time, was sacred and the public was forbidden from sailing on its waters. It’s a wonder why Caligula would have such remarkably large ships built for such an insignificant body of water, but being so private, perhaps it’s where he found his solace (or lived out his debauchery).

On the one hand, it’s impressive to consider the possibility that a single pair of men could have secretively developed and employed such a contraption without going noticed. On the other, it’s a wonder that they could ploy the depths of a relatively deep volcanic lake (108 feet max), naked, without losing their very manhood.

Read more at Ancient Origins, and read Dr. Eliav’s article here. –OJB

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