 It appears it would have been difficult to flood the amphitheatre, but, because few records survive on the operation of the Colosseum, it is impossible to say for certain where the naval battles took place. Suetonius writes that Titus'brother and successor, Domitian, staged sea-fights in the amphitheatre, but he had made alterations to the structure, which probably included adding the hypogeum — a complex of underground passages that may have allowed the arena to be quickly flooded and emptied. While Suetonius only records that Titus' recreations of naval battles took place, Dio gives some details:
