Naumachia, (Latin, derived from Greek: “naval battle”) plural naumachiae, in ancient Rome, a mimic sea battle and the specially constructed basin in which such a battle sometimes took place. These entertainments also took place in flooded amphitheatres. The opposing sides were prisoners of war or convicts, who fought until one side was destroyed.

The earliest naumachia recorded (46 bc) represented an engagement between the Egyptian and Tyrian fleets and was given by Julius Caesar on an artificial lake that was constructed by him in the Campus Martius. In 2 bc Augustus staged a naumachia between Athenians and Persians in a basin newly constructed on the right bank of the Tiber at Rome. In the naumachia arranged by Claudius on Lake Fucino in ad 52, 100 ships and 19,000 men participated.

A later version of the naumachia was practiced in indoor theatres, such as London’s Sadler’s Wells, during the 19th century. A tank was constructed in the pit and stalls areas, and real boats were used for the purpose.