Metrication in the United States traditional mile-based lengths. In the Olympics, athletes run 1500 meters, not 1600 meters. Running races in the U.S. are usually run in metric distances (e.g., the 100 metres dash or the 5K run), although the mile distance remains popular. But even 5 and 10 kilometer races most often have mile markers on the course, and no kilometer markers. Long-distance races are often measured in kilometers, although exceptions exist (generally 10 mile races). The marathon is referred to as a 26.219-mile race (the official marathon standard distance originally being in English units — 26 miles, 385 yards) rather than 42.195 km.
Long-distance swimming Some of the better-known long-distance swims are crossings of the English Channel, Catalina Channel, Fehmarn Belt and Cook Strait. Ultra-long distance swimming is sometimes referred to as marathon swimming. The minimum distance that constitutes a marathon swim has dramatically shortened over time. Different organizations adopt various minimum distances. The swimming marathon events at the Olympic games have a distance of 10 km. Long-distance swims tend to fall into one of two categories: (1) swims in which the start date and start time are chosen by the individual swimmer (often called solo-swims), and (2) swims that involve a group-start. Long-distance swimming