A drydock (also commonly dry dock) is a narrow basin or vessel that can be flooded to allow a load to be floated in, then drained to allow that load to come to rest on a dry platform. Drydocks are used for the construction, maintenance, and repair of ships, boats, and other watercraft.

According to the ancient Greek author Athenaeus of Naucratis (V 204c-d), the drydock was invented in Ptolemaic Egypt, some time after the death of Ptolemy IV Philopator (reigned 221-204 BC):

Since Athenaeus recorded the event 400 years later (around 200 AD), there is sufficient reason to believe that drydocks had been known throughout classical antiquity. The Roman shipyard at Narni, Italy, which is still studied, may have served as a dry dock.

The use of drydocks in China goes at least as far back the 10th century A.D. In 1088, Song Dynasty scientist and statesman Shen Kuo (1031–1095) wrote in his Dream Pool Essays:

The first early modern European and oldest surviving drydock still in use was commissioned by Henry VII of England at HMNB Portsmouth in 1495 (see Tudor navy). This drydock currently holds the world's oldest commissioned warship, HMS Victory.

Dry or dryness denotes a lack of water. It may also refer to

Dock may refer to: