A mariner's cap also called a skipper's cap, sailor's cap, Dutch Boy's cap, or fiddler's cap, is a peaked cap, usually made from black or navy blue wool felt, but also from corduroy or blue denim. Originally popular with seafarers, it is often associated with sailing and maritime settings, especially fishing, yachting and recreational sailing. It has sometimes become a fashion item in the West, for example being worn by John Lennon in the mid-1960s.

Fashion of the 1960s featured a number of diverse trends, as part of a decade that broke many fashion traditions, adopted new cultures, and launched a new age of social movements. Around the middle of the decade, fashions arising from small pockets of young people in a few urban centers received large amounts of media publicity, and began to heavily influence both the haute couture of elite designers and the mass-market manufacturers. Examples include the mini skirt, culottes, go-go boots, and more experimental fashions, less often seen on the street, such as curved PVC dresses and other PVC clothes.