Did the Romans Really Stage Sea Battles in the Colosseum?

Yes. Naval battles — called naumachiae — were among the most extravagant spectacles Romans staged, and at least one was held at the Colosseum during Emperor Titus’s inaugural games of AD 80. The arena was flooded to sufficient depth to float reduced-scale warships, thousands of combatants fought in reenactments of famous historical battles, and the mechanism drew on Rome’s exceptional hydraulic engineering. The Colosseum’s naumachia capability was short-lived: once Emperor Domitian built the underground hypogeum in the 80s–90s AD, flooding the arena became impossible and later naumachiae moved to purpose-built basins elsewhere in Rome.

Naumachia Quick Facts

  • Meaning: from Greek naumachia, “naval battle”
  • First recorded: 46 BC, Julius Caesar’s games in a purpose-built basin
  • Colosseum naumachia: AD 80, during Titus’s inaugural games
  • Typical reenactments: Salamis (480 BC), Corinth, Actium
  • Combatants: thousands per event, often condemned prisoners
  • Specialised basins: Naumachia Augusti (across the Tiber), Naumachia Traiani (under Trajan)
  • Ended at the Colosseum: when the hypogeum was built, making flooding impossible

What Was a Naumachia?

A naumachia was a staged naval battle presented as public entertainment, typically reenacting a famous historical engagement. Combatants fought on reduced-scale warships in a flooded arena or purpose-built basin, and the action combined the visual drama of shipboard combat with the logistics of large-scale maritime choreography. Casualties could be severe — Roman sources describe naumachiae in which thousands died — and the spectacle was understood as more extreme and more expensive than conventional gladiatorial combat.

The form originated under the late Republic. Julius Caesar held the first recorded naumachia in Rome in 46 BC, during his quadruple triumph celebrations, using a purpose-dug basin. Augustus staged another in 2 BC to celebrate the dedication of the Temple of Mars Ultor, using a permanent basin across the Tiber. By the early imperial period, naumachiae had become an established but rare element of spectacular public festivities.

Which Battles Were Reenacted?

Three historical engagements appear repeatedly in the sources as subjects of naumachia reenactments.

Salamis

The 480 BC Greek naval victory over the Persian navy under Xerxes. This was the subject of the Colosseum’s inaugural-games naumachia under Titus, and one of the most frequently reenacted battles because of its historical fame and dramatic narrative.

Corinth

Various naval engagements involving Corinth in Greek history, used by some imperial naumachiae as an alternative classical reference.

Actium

Augustus’s 31 BC naval victory over Antony and Cleopatra, which established his supremacy. Reenactments of Actium had powerful political resonance as propaganda for the emperor’s dynasty.

Sponsors typically chose battles with recognisable names and clear narrative arcs. The goal was public spectacle, not precise historical reconstruction, and the engagements were simplified and compressed for arena presentation.

How Was the Colosseum Flooded?

The mechanism is debated because no detailed technical account survives, but the outline is clear. In AD 80 the Colosseum had no underground — the hypogeum was not built until under Domitian — and the arena floor rested directly on earth. Water could therefore be introduced from Rome’s aqueduct system and contained within the arena oval by waterproofing the floor and supporting walls.

Estimates of the required water depth vary from roughly half a metre (sufficient to float small skiffs and suggest a naval engagement) to approximately 1.5 metres (adequate to float reduced-scale warships with shallow draught). Neither extreme is certain. The operation required dedicated aqueduct supply — one of Rome’s major aqueducts could have filled the arena in several hours — and drainage channels to empty the arena afterward.

The technical demands were substantial. Waterproofing a temporary basin of the Colosseum’s dimensions required sealing the floor and lower walls with materials (pozzolana concrete, possibly coated with lead or pitch) that could withstand hydrostatic pressure. The drainage had to move tens of thousands of cubic metres of water without flooding the surrounding city. That the Romans achieved this, even once, confirms the extraordinary capability of their hydraulic engineering.

What Happened at the Colosseum’s Naumachia?

The AD 80 event is recorded by several sources, none at great length. Cassius Dio provides the main account. The reenactment of Salamis included both Athenian and Persian ships (identified by costume and equipment), thousands of combatants drawn primarily from condemned prisoners, and a full engagement followed by the ritual destruction of the “losing” side. Martial’s Liber de Spectaculis references the event in passing, celebrating the transformation of the arena into a naval battlefield.

The occasion appears to have been singular at the Colosseum. No subsequent naumachia at the amphitheatre is recorded, and the construction of the hypogeum under Domitian removed the physical possibility. The AD 80 event thus marks both the beginning of the Colosseum’s history as a spectacle venue and the end of its viability for naval reenactments.

Where Else Did Naumachiae Take Place?

Two major permanent naumachia basins operated in Rome. The Naumachia Augusti, built by Augustus in 2 BC across the Tiber in the area later known as Trastevere, was an artificial basin roughly 530 metres long by 360 metres wide — large enough for full-scale warships and thousands of combatants. It remained in use for several centuries.

The Naumachia Traiani, built by Emperor Trajan in the early second century AD, replaced the Augustan basin’s function with a newer facility. It operated through the later imperial period until water supply and maintenance costs became prohibitive.

Other amphitheatres outside Rome occasionally staged smaller naumachiae, but the spectacle was always rare and expensive. The permanent basins allowed recurring events without the structural demands of flooding a general-purpose amphitheatre; the Colosseum’s AD 80 naumachia was exceptional precisely because it was staged in a building primarily designed for other purposes.

Who Fought in Naumachiae?

Participants were typically condemned prisoners rather than trained gladiators. The scale of casualties — thousands killed in a single event — exceeded what the gladiator schools could have sustained, and naumachia fighters (naumachiarii) were a separate category of arena performer, generally expected to die in large numbers.

Claudius’s famous AD 52 naumachia on Lake Fucinus — staged before a major engineering project to drain the lake — is the source of the phrase morituri te salutant (“those who are about to die salute you”). Suetonius records that the combatants called out this line to the emperor before the battle; Claudius reportedly replied that perhaps they would not die, and the combatants took this as permission not to fight, requiring further persuasion to begin. The phrase is attested only from this specific event and should not be understood as a general gladiatorial formula.

Did Naumachiae Die Out?

They became progressively rarer after the first century AD. The expense — water supply, specialised equipment, large numbers of combatants — was enormous, and later emperors found simpler spectacles more economical. The last recorded major naumachia in Rome dates to the third century AD, and the practice faded entirely by the Christianisation of the Empire in the fourth century.

At the Colosseum specifically, the naumachia capability ended with the construction of the hypogeum under Domitian. What began as the building’s opening spectacle became permanently impossible within a decade and a half, making the AD 80 event a unique moment in the amphitheatre’s history.

Frequently Asked Questions

Did the Colosseum really flood for sea battles?

Yes, at least once — during Emperor Titus’s inaugural games in AD 80. The flooding required dedicated aqueduct supply and waterproofing of the arena. Once Domitian built the hypogeum later in the first century, flooding became impossible.

How deep was the water for naumachiae?

Estimates vary from approximately 0.5 to 1.5 metres depending on the specific event and whether full-scale or reduced-scale warships were used. The exact depth at the Colosseum’s AD 80 naumachia is not precisely recorded.

Were the combatants trained sailors?

Usually not. Naumachia fighters were typically condemned prisoners or enslaved combatants, not professional sailors. The expected fatality rate made trained specialists too expensive to deploy in these numbers.

What famous battle was reenacted at the Colosseum?

The AD 80 inaugural games naumachia reenacted the Battle of Salamis — the 480 BC Greek naval victory over the Persian navy. Later naumachiae at other venues reenacted Actium, Corinth and other famous engagements.

Is there evidence of the Colosseum’s naumachia in the building today?

Not directly. The hypogeum’s construction under Domitian obliterated any physical traces of the flooding infrastructure used in AD 80. What survives is the literary record confirming the event took place.

Understand the Arena’s Full Capability on a Tour

Our Colosseum tours discuss the arena’s short-lived naumachia capability as one of the building’s most extraordinary early uses, placing the inaugural games in their full spectacular context. Understanding what the arena could once do — before the hypogeum closed off the possibility — changes how the surviving structure reads to visitors today.