The list of units
The galley is the first naval unit you can build. These tiny, primitive ships must end each turn in a coastal square -- they are in danger of sinking if they end their turn in a sea or ocean square. If The Great Lighthouse is built, galleys may safely end turns at sea, but never ocean squares.
The galley was the first ship designed for war. Introduced by the Greeks, galleys were powered by banks of oars on each side, manned by well-trained oarsmen. These oarsmen were highly paid professionals or patriotic citizens, not slaves and prisoners as depicted in fiction. A huge, bronze "beak" mounted at the bow of the ship was used to ram and sink enemy ships. Because of its long, narrow hull, the galley was very unstable in all but the calmest waters, and as a consequence its crew rarely ventured out of sight of land for long periods of time, lest the ship be caught in a storm and sunk.