"Now you too can experience the joys of sea sickness without having to set foot on a boat!"
Called "dazzle" camouflage, the idea was to cover the ships in psychedelic designs that made it damn nigh impossible for an enemy spotter to determine speed, distance, and type of craft when spying the ships from afar. Try to stare hard at one of these -- your brain will start to hurt:
It's like nautical Magic Eye.
The camouflage saw widespread use during World War I and (to a lesser degree) World War II, but it ultimately died out when the introduction of LSD allowed enemy spotters to operate on the same plane of consciousness as those creating the designs.