A trireme is a type of human powered galley that was widely used in the ancient world. The word trireme refers to the three vertical rows of oars that the vessels had on each side, an advancement over earlier one row penteconters and two row biremes. Each oar was typically operated by a single person, though the exact configuration and design of these vessels was lost by the Middle Ages. Later galleys that used three oar banks are also sometimes referred to as triremes, though their designs may differ from the original warships of antiquity. Modern recreations of triremes are sometimes built and operated, and one participated in the Olympic torch relay in 2004.
During classical antiquity, between the seventh and fourth centuries BCE, the trireme was one of the most successful warships. The vessels were reportedly both fast and maneuverable, due to using three vertical banks of oars. Sources disagree on when and where they were first used, though reliable evidence points to their use when Persia invaded Egypt in 525 BCE. Triremes were also instrumental in the establishment of Athenian maritime dominance, until they were used by both sides when Sparta and its allies defeated Athens at Aegospotami.
There is no definitive evidence as to the exact design of ancient triremes. Most modern knowledge of these vessels comes from written accounts and artwork, as no preserved wrecks have ever been discovered. One innovation thought to have existed in Athenian triremes was a set of cables referred to as hypozomata. These cables are thought to have been rigged under the beam and tensioned to prevent hogging in rough seas. The tension provided by the cables may also have allowed an Athenian trireme to ram an enemy vessel without breaking apart.
Historical sources referred to triremes as being two cubits long, which is equivalent to about 37 meters (120 feet). These descriptions are thought to be fairly accurate, as building sheds of roughly this length have been unearthed in ancient Athenian shipyards. The dimensions of these sheds and ancient references suggest that the vessels were about three meters (nine feet) tall. Trireme hulls are thought to have been constructed of soft woods, such as pine and fir, which tend to be light and allow for faster vessels. A typical trireme is thought to have had about 170 oars arranged in sets of three vertical rows, along with a pair of rear steering oars and two square-rigged masts.
In the 1980s, a project was undertaken in Greece to recreate a classical trireme. This project used ancient sources to approximate the construction as best possible and led to many new discoveries about the probable conditions and capabilities of the vessels. Even operating with a relatively inexperienced crew, this recreated trireme was able to achieve speeds of 9 knots (about 17km/h) and perform relatively tight turns.