The Marathon is a classic long-distance foot race; the standard distance is 42.195 km (26 miles, 385 yards) though there is some variation between courses. The awkward distance was fixed for the first time for the 1908 Olympic games in London - as legend has it to ensure a final stretch in front of the Royal Box as well as a starting point at Windsor Castle.
More than 500 marathon races are held annually, most of them as road races, though the distance can also be pursued cross-country. For the vast majority of runners, it is not so much a race as an endurance test; they will be happy just to finish, whatever their time, though many compete with themselves hoping to beat their previous times. For others, it is very much a competitive sport; there are substantial cash prizes for some races and the marathon has been an Olympic event since 1896. By tradition, the medals for the men's marathon are always the final ones to be awarded at the Summer Olympics, with its medal ceremony being incorporated into the closing ceremony. In the 21st century, marathons have a tendency to be dominated by runners from Ethiopia and Kenya, though Japan is also a powerhouse in women's marathons.
The name commemorates the battle of Marathon in 490 BC; the Athenians and some allies soundly defeated a Persian invasion force that had just come off ships near the small town of Marathon; according to legend, an army messenger ran non-stop to Athens with the happy news and dropped dead immediately after delivering it. The length of the race is based on the legend and his most likely route. This may not be entirely accurate since a runner might have taken a shorter but hillier alternate route, and the ancient Greeks had horses so they might not have sent a runner at all.
There are ultramarathon races which cover even longer distances. Perhaps the most challenging footrace of all is the Marathon des Sables (Marathon of the Sands), 250 km (156 miles) across part of the Sahara Desert in Morocco.
There is also a triatholon called Ironman; despite the name, women do compete in this event, and the best of them are faster than most men. It starts with a 4 km swim, then 180 km of cycling and finally running a marathon distance. There are several dozen events a year and an annual Ironman World Championship in Hawaii.
Many cities host large and prestigious marathons, each attracting top marathoners and huge crowds of non-professional runners. Climate is a major factor in the choice of dates; in the tropics most events are held in winter, elsewhere in spring or fall.
There is an every-two-years championship series called the World Marathon Majors which includes an IAAF marathon every two years, the Olympic marathon every four, and six annual city marathons:
Other cities with marathons include:
Many people travel for marathons, so lodging selection is important. For major marathons the influx of visitors can overwhelm local lodging options, so plan to book well in advance. Marathons will typically involve shutting down the roads along the course, so transportation to the starting line on race day can be tricky - if you can book a hotel that is close to public transit or near the starting line your marathon experience is likely to be much less stressful.
Particularly if you aren't an experienced marathoner, expect to feel pretty brutalized after completing the course. Most people won't want to spend hours driving or on a plane immediately after putting their body through twenty-six miles of punishment, so booking a hotel for multiple nights - at least the night before and the night after the marathon - is a plan that you are unlikely to regret.
According to legend, the first marathon runner dropped dead just after finishing the run. That story may not be accurate, but certainly a marathon puts considerable strain on the body. No-one should attempt the race, or even serious training for it, without first talking to their doctor.
There are two water-related dangers; dehydration is uncomfortable, debilitating and dangerous, quite definitely not good for you. On the other hand excessive consumption of fluids can lead to hyponatraemia, a reduction of sodium levels in the blood that is sometimes fatal for long-distance runners. Wikipedia has some good general advice on the topic, but you need precise advice tailored to your body; consult a doctor with expertise in sports medicine.
Many competitors find it necessary to work out a detailed hydration plan in advance so that they can avoid both dehydration and hyponatraemia on race day.
Some marathons are run at high altitudes; for those, altitude sickness is an issue. Anyone should at least give themselves a few days to acclimatize before the race, and consider adjusting their hydration plan since altitude can also cause dehydration. Serious competitors will need to train at altitude, and most of the top Ethiopian and Kenyan runners grew up at high altitude.