A surfboard is a narrow plank used in surfing. Surfboards are relatively light, but are strong enough to support an individual standing on them while riding an ocean wave. They were invented in ancient Hawaii, where they were known as papa he'e nalu in the Hawaiian language, they were usually made of wood from local trees, such as koa, and were often over 460 cm (15 ft) in length and extremely heavy. Major advances over the years include the addition of one or more fins (skegs) on the bottom rear of the board to improve directional stability, and numerous improvements in materials and shape.
Modern surfboards are made of polyurethane or polystyrene foam covered with layers of fiberglass cloth, and polyester or epoxy resin. The result is a light and strong surfboard that is buoyant and maneuverable. The Polystyrene surfboard was invented by Reginald Sainsbury of Wilcove, Torpoint in the early 1960s whilst working for the Poron Insulation company, Millbrook, Cornwall who were looking to expand into the leisure industry. Recent developments in surfboard technology have included the use of carbon fiber and kevlar composites, as well as experimentation in biodegradable and ecologically friendly resins made from organic sources. Each year, approximately 400,000 surfboards are manufactured.