A marathon run is defined as 26.2 miles or 42.195K, but what is the definition of a marathon swim? It depends who you talk to.
A marathon swim is defined by FINA 10 kilometers (6.2 miles) in length with the Olympic 10KM Marathon Swim as its most visible race.
The Atlantic City Around-the-Island Marathon Swim is 37 kilometers (22.5 miles) in length.
The Tampa Bay Marathon Swim is 38.6 kilometers (24 miles) in length.
The Manhattan Island Marathon Swim is 46 kilometers (28.5 miles) in length.
The Maratona Del Golfo Capri-Napoli in Italy is 36 kilometers in length.
The Maraton Acuatica Internacional Santa Fe - Coronda in Argentina is 57 kilometers in length.
The Sumidero Canyon Swimming Marathon in Mexico is 15 kilometers in length.
The Maraton Acuatico Internacional Ciudad Rosario in Argentina is 15 kilometers in length.
The Maraton Patagones Viedma in Argentina is 15 kilometers in length.
The Ohrid Lake Swim Marathon in Macedonia is 30 kilometers in length.
The Galata Varna Swimming Marathon is 4 kilometers in length.
The Self-Transcendence Marathon Swim is 26.4 kilometers in length.
The PT109 Commemorative Swim Marathon is a 5 kilometer swim in the Solomon Islands.
According to the venerable Ted Erikson, in the 1960's, 16 kilometers (10 miles) was referred to as a marathon swim because of the relative times involved for completion.
Wikipedia refers to marathon swimming as 10 kilometers in distance, referring to the FINA definition.
Timothy Johnson describes a slew of marathon swims of various lengths in his authoritative book, History of Open Water Marathon Swimming (see book cover above).
Conrad Wennerberg also provides a rich description of marathon swims in his book, Wind, Waves, and Sunburn: A Brief History of Marathon Swimming.
The Canadian Encyclopedia defines marathon swimming as swimming in open water for distances in excess of 1500 meters.
The Encyclopedia of New Zealand defines marathon swims as longer than 10 kilometers.
Neither US Masters Swimming nor USA Swimming define marathon swimming.
The World Professional Marathon Swimming Federation was formed in 1963 by professional marathon swimmers themselves and was the effective governing body of the sport for several decades. Its shortest swim was 16 kilometers in length.
Sports Illustrated has written about marathon swimming over the years. In one article, the magazine described one marathon swim by by Diane Nyad as 10 miles in length.
The International Marathon Swimming Hall of Fame defines marathon swimming as 25 kilometers in length.
Tony Lyons has a specific definition of a marathon swim: he is going to swim 42 kilometers (26 miles) or 1688 laps in a 25-meter pool in British Columbia, Canada in March 2009 to raise funds for the CKNW Orphan’s Fund.
Others define marathon swims as the distance of the English Channel (33 kilometers).
From our perspective here at The Daily News of Open Water Swimming, everyone has a good reason or valid justification for believing their definition of a marathon swim is correct.
At the same time, given the exposure that marathon swimming has received from its inclusion in the Olympics, the sport may be best served by keeping in line with FINA and the IOC.
Footnote: a 10-kilometer swim done by a world-class swimmer is comparable in time to a marathon run done by world-class marathon runners. It should be noted that the marathon run distance was standardized in 1921 after various distances had been debated since the 1st century AD. We are hopeful the marathon swimming community will come to an agreement in a shorter time frame than its running counterparts.