Ships need solid edges to work against. A dock is a structure or basin where vessels can be moored for loading, unloading, repair, or storage, often with gates that control water level.

Wet docks maintain a constant water level behind lock gates; dry docks can be drained entirely for hull access. The term is also used more loosely for any berth or quay. Dock systems include walls, fenders, bollards, and often cranes and warehouses.

Dock capacity and depth limit the size of ships that can use a port. Maintenance of dock walls and gates is expensive but essential. A ship “in dock” may be alongside for cargo or fully out of the water for survey and repair.

• Structure or basin for mooring and working ships
• Includes wet docks and dry docks
• Equipped with fenders, bollards, and cargo gear
• Determines accessible ship size for a port