1.2 in endurance sports generally refers to the 1.2 mile swim distance of a Half Ironman, also known as 70.3. Triathletes swim this distance in an open water setting, usually a lake, river or ocean. Athletes start their 1.2 mile swim either as a mass start, rolling start or age group start.
There are various other distances in the sport of open water swimming or triathlon, including the Ironman distance of 2.4 miles all the way up to the 10k open water distance generally used for Olympic open water swimming.
