Ship camouflage is a form of military deception in which a ship is painted in one or more colors in order to obscure or confuse an enemy's visual observation. Several types of marine camouflage have been used or prototyped: blending or crypsis, in which a paint scheme attempts to hide a ship from view; deception, in which a ship is made to look smaller or, as with the Q-ships, to mimic merchantmen; and dazzle, a chaotic paint scheme which tries to confuse any estimate of distance, direction, or heading. Counterillumination, to hide a darkened ship against the slightly brighter night sky, was trialled by the Royal Canadian Navy in diffused lighting camouflage.
Ships were sometimes camouflaged in classical times. Mediterranean pirate ships were sometimes painted blue-gray for concealment. Vegetius records that Julius Caesar's scout ships were painted bluish-green when gathering intelligence along the coast of Britain during the Gallic Wars. Ships were sometimes painted deceptively during the Age of Sail, while both sides in the American Civil War camouflaged their ships, whether to run blockades or for night reconnaissance.
Ship camouflage was used in earnest by the British Admiralty in the First World War. The marine artist Norman Wilkinson led research into dazzle camouflage, resulting in the painting of thousands of British and later American ships in dazzle patterns. He intended it not to make ships invisible, nor even to cause the enemy to miss his shot, but to deceive him into taking up a poor firing position. In the Second World War, dazzle was revisited by the Royal Navy and the United States Navy, and applied to a limited extent by other navies.
After the Second World War, radar made painted camouflage less effective, though inshore craft continue to use camouflage schemes alongside anti-radar stealth.