Marathon Swimming at the 2008 Summer Olympics

Marathon swimming, often called open-water swimming, made its Olympic début at the Beijing 2008 Olympic Games. A single race for men and women was conducted over 10 km each. The races were held at the Shunyi Olympic Rowing-Canoeing Park (Shunyi Aolinpike Shuishang Gongyuan) in Mapo Town in the Shunyi District of Beijing, which was also the venue for the sprint canoeing and rowing events.

Each event had 25 swimmers, with 23 nations represented among the women and 24 among the men. Brazil and Great Britain had two female swimmers each and Russia had two male swimmers. Overall, 31 nations competed in open-water swimming.

Marathon swimming had been contested at the World Aquatics Championships since its 1991 edition in Perth, Australia, where men and women raced over 5 km, 10 km, and 25 km. Open-water swimming has been around much longer than that, however, as many races in the 19th and early 20th century were held in open water, including the swimming events at the Athinai 1896, Paris 1900, St. Louis 1904 Olympic Games, and the Athinai 1906 Intercalated Olympics.