In FINA-sanctioned international races, the following rules apply:

▪ Open water swimming courses are clearly marked with distance markers, turn buoys and, occasionally, mid-course buoys, ropes or lines.

▪ In international events, swimmers must wear a transponder on each wrist for timing and finishing results. Athletes are disqualified for finishing without the transponders.

▪ Coaches (one per swimmer) are permitted to give their athletes instructions, food and drink for the 10K and 25K races. In the 10K races, coaches give drinks to the athletes from docks, piers or floating feeding pontoons. In the 25K races, coaches give drinks and gel packs from individual escort boats.

▪ Boats with the Head Referee, technical officials, medical personnel, media representatives and photographers are permitted on the course.

▪ Athletes start races in front of the rope during in-the-water starts or by diving from a floating start platform, depending on the race course.

▪ Athletes can be disqualified for making intentional contact, obstruction or interference with another swimmer. Such unsportsmanlike conduct is judged solely by the Head Referee, who is located in an escort boat.

▪ Warnings are given with a whistle by the Head Referee. At the first rule infraction, the Head Referee shows a yellow flag to the athlete with a card bearing their number. For the second infringement, athletes are shown a red flag and a card bearing their number, and can be asked to immediately leave the water.

For a complete summary of FINA race rules, please see
http://www.fina.org/rules/english/openwater.php