Did the Romans Fight Naval Battles in the Colosseum?

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The trailer for Gladiator II has just dropped, rekindling the world’s interest in Roman history.

Filling the shoes – or indeed sandals – of Russell Crowe’s Maximus is one of the toughest tasks in Hollywood. But, at least at first glance, it seems like this movie delivers. Some stellar casting (Denzel Washington as Macrinus; Paul Mescal as Lucius Verus), blockbuster special effects, and enough blood and sweat to fill a Roman arena look likely to win over a new generation of gladiator fanatics. But the trailer has raised eyebrows among a few historians. 

Some are questioning the casting and portrayal of co-emperors Caracalla and Geta. Caracalla would later murder Geta after an unsuccessful joint rule in which they seldom shared the same company, living in separate parts of the palace. Others are drawing attention to the presence of a rhinoceros in the Colosseum and a later memorable scene that depicts the amphitheatre's flooding. 

Given that its writer was behind the rip-roaring but historically illiterate Napoleon (2023), some historical inaccuracies should be expected. But it's the flooding of — and fighting of naval battles in — the Colosseum that we're focussing on today.

Did the Romans flood the Colosseum?

Put simply, we don’t know. Even our ancient sources are in disagreement. But we can make an educated guess based on the available evidence. 

Firstly, some of our ancient authors attest to the Colosseum being flooded. The historian Cassius Dio, writing at the beginning of the third century CE, tells us that”

[The emperor] Titus suddenly filled this same theatre with water and brought in horses and bulls and some other domesticated animals that had been taught to behave in the liquid element just as on land. He also brought in people on ships, who engaged in a sea fight there, impersonating the Corcyreans and Corinthians.”

Cassius Dio was writing more than 100 years after the events he described, making his use as a primary source problematic. But the poet Martial, a contemporary of the Colosseum’s inauguration, also refers to the amphitheatre being flooded (albeit in more ambiguous language).

“If you are here from a distant land, a late spectator for whom this was the first day of the sacred show, let not the naval warfare deceive you with its ships, and the water like the sea: here but lately was land. You don't believe it? Watch while the waters weary Mars. But a short while hence you will be saying: 'Here but lately was sea’.”

Technically, the Colosseum could have been flooded during its inaugural year (80 CE) – at least until the construction of its underground (hypogeum). Following the construction of this vast network of tunnels and storage rooms beneath the arena floor, waging water battles at the Colosseum would no longer have been possible. 

Immerse yourself in ancient Rome on our Colosseum Arena Tour

The tricky logistics of flooding the Colosseum

Because the Colosseum’s underground area has changed beyond recognition, it’s impossible to reconstruct how flooding it would have worked. Flooding such a huge space in a short amount of time would be a tough task even now, but how might the Romans have done it? 

Granted, their aqueduct system brought in sufficient volumes of water for it to be feasible. The Claudian Aqueduct alone could discharge 1.6 m3 (1600 litres / 423 galleons) per second after being piped from its distribution tank on the Caelian Hill.

Assuming that the circumference of the Colosseum’s arena measured 80 by 45 metres, the civil engineer academic Martin Crapper has calculated that the arena of the Colosseum (4241 m3) could have been filled in between 2-5 hours, depending upon where the flow was measured and assuming that all the water was diverted for that purpose. 

This does seem to contradict Cassius Dio’s claim that it seemed the emperor Titus had "suddenly filled this same theatre with water" (Dio, LXVI.25.2). That said, over a full day at the Colosseum, the speed with which the arena filled with water may well have seemed exceptional.

Could another amphitheatre provide the answer? 

Luckily for us, the beautifully preserved amphitheatre of Verona gives us an idea of how the Colosseum might have been flooded. 

Beneath the Veronese arena, there’s a basin connected to two axial conduits, one of which would have been connected to an aqueduct to fill the basin. The other was designed to drain water out again into the River Adige.

Did the Romans fight naval battles in the Colosseum?

If the Colosseum was indeed flooded, this was done to accommodate naval battles (naumachia, as they were called in Latin). Rome first hosted such staged naval battles in 46 BC following Julius Caesar’s quadruple triumph (celebrating his subjugation of Gaul (modern France), Egypt, King Pharnaces of Pontus and King Juba of Numidia). 

Caesar ordered the excavation of a basin close to the River Tiber, and the creation of an artificial lake around 1,800 feet long and 1,200 feet wide. This artificial lake was surrounded by marble seating to accommodate Rome’s wealthy spectators and more than 3,000 men aboard 12 Roman galleys fought a sea battle to the death, drawing in crowds from all over Italy. 

We have reason to believe that this ‘aquatic amphitheatre’ was located in today’s district of Trastevere and that its remains may lie beneath the modern Piazza of San Cosimato.

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Plan of Augustus’s Naumachia which underlies today’s Trastevere district

Caesar’s successor, Augustus, also put on naval battles in Rome. But he hosted them not in the Colosseum (which would be inaugurated only 66 years after Augustus’s death) but in his own naval arena, which was completed in 2 BCE. The imperial biographer Suetonius tells us that Titus hosted his naval battles in “the old” Naumachia arena, and there’s an argument to be made that Cassius Dio would later confuse this arena for the Colosseum.

If this is indeed the case, it suggests that naval battles did not take place in the Colosseum.

Are those sharks swimming around the Colosseum?

The trailer also shows what appear to be sharks (or dolphins?) swimming around the arena. Since few species can survive outside saltwater, this is quite obviously ridiculous. Yet it does depict the exoticism that the Colosseum’s event organisers exhibited. 

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We know from frescoes from nearby Ostia Antica, Rome’s ancient port, that this settlement was a hotspot of Rome’s exotic animal trade.

One mosaic from the mercantile Forum of the Corporations shows a North African elephant; another shows the loading of a trade ship.

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Elephant mosaic from Ostia Antica’s Forum of the Corporations. Photo credit: Wikimedia Commons

Bears, panthers, leopards and indeed lions were slaughtered inside the Colosseum in a series of spectacles that the Romans called bestiarii. Some animals were sourced for venationes, wild animal hunts that pitted trained fighters against beasts. Other wild animals (often lions, tigers or panthers), were set upon the condemned as a form of public execution in a sinister spectacle called damnatio ad bestias (condemnation to the beasts).

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Alexander Meddings
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Alexander Meddings is a professional copywriter and postgraduate in Roman history from the University of Oxford. After graduating with his MPhil, he moved to Florence and then Rome to carry out his research on the ground and pursue his passion at the source. He now works in travel, as a writer and content consultant, and in education as a university lecturer and translator.
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