Swimming at the 2012 Summer Olympics – Men's marathon 10 kilometre

The men's marathon swim over a distance of 10 kilometres at the 2012 Olympic Games in London took place on 10 August in the Serpentine at Hyde Park.

Outclassing a vast field of rivals, Tunisia's Oussama Mellouli built a historic milestone as the first ever swimmer to capture Olympic titles in both pool and open water. Around the 7 km mark, Mellouli quickly opened up a three-body-length lead over a small pack of swimmers, and maintained a fast pace to claim his second gold and third career medal in 1:49:55.1. Chasing for two more Olympic medals in a grueling race, Germany's Thomas Lurz finished behind the leader by 3.4 seconds with a silver in 1:49:58.5, while Canada's Richard Weinberger, who pulled off a powerful lead on the first lap, grabbed the bronze in 1:50:00.3.

Greece's Spyridon Gianniotis, the reigning world champion, mounted a spirited challenge against Mellouli, Lurz and Weinberger in pursuit, but dropped back in the last 200 metres to fourth in 1:50:05.3. Enjoying a massive support from the home crowd at Hyde Park, Great Britain's Daniel Fogg struggled to maintain his form after the fourth lap, but pushed himself further from behind with a spectacular swim to claim a fifth spot in 1:50:37.3. Fogg was followed in sixth and seventh respectively by Russian duo Sergey Bolshakov (1:50:40.1) and Vladimir Dyatchin (1:50:42.8), while Lurz's teammate Andreas Waschburger, who led both the third and fourth lap ahead of Mellouli and Weinberger, faded down the stretch to pick up the eighth spot in 1:50:44.4. Bulgaria's four-time Olympian Petar Stoychev finished ninth in 1:50:46.2 to hold off an American open water swimmer Alex Meyer (1:50:48.2) by exactly two seconds.

As the remaining swimmers completed the race, Guam's 16-year-old teen Benjamin Schulte fought off audaciously throughout the open-water course to round out the field with a twenty-fifth place time in 2:03:35.1.

Qualification
The men's 10 km open water marathon at the 2012 Olympics featured a field of 25 swimmers:
 * 10: the top-10 finishers in the 10 km race at the 2011 FINA World Championships.
 * 9: the top-9 finishers at the 2012 Olympic Marathon Swim Qualifier (8–9 June 2012 in Setúbal, Portugal).
 * 5: one representative from each FINA continent (Africa, Americas, Asia, Europe and Oceania). (These were selected based on the finishes at the qualifying race in Setúbal.)
 * 1: from the host nation (Great Britain) if not qualified by other means. If Great Britain already had a qualifier in the race, this spot was allocated back into the general pool from the 2012 qualifying race.