Wildwater canoeing is a timed event consisting of two forms of racing, classic and sprint. When the sport began only the longer-distance format (now known as classic) was in use until a shorter sprint version was also later introduced. Wildwater courses can contain class two to class four whitewater, with classic courses varying from three to six miles in length (10 to 35 minutes) and sprint courses between 200 and 600 metres (one minute). Some paddlers specialise between the two formats, but the majority compete in both.