"Swimrun is a bit like aquathlon meets adventure racing except you don't change your clothes - you finish the race in what you started with, so most people swim in trainers and run in their wetsuit. This might challenge you but it is not as hard as you think, in fact the effects of muscle cooling on the legs and the multi transisitions often mean you can keep moving for longer.
Most swimruns are in teams of two, your race partner forms part of your safety, your motivation and provides a great shared experience. This aspect of swimrun racing promotes a social and caring race atmosphere.
There's no official Standard/Sprint/Long/Middle/Short/Ultra distances in swimrun. The distances are defined by the landscape, and how each Race Director plots a journey through that landscape.
That said most swimruns are in the region of 25km to 45km in total with around 10-20% of the total distance being swimming. A "sprint" might roughly be defined as <10km, and an "Ultra" >80km. Each race website gives full details on distances, percentage of swimming & running, and height gain. Seeing the detail of each swimrun before you enter is part of the excitement and attraction of swimrun.
It is a growing global sport with great flexibility in it's format and locations. There are some solo races, some races that don't have a mandatory wetsuit rule, some races with teams of four... the scope for growth is as big as the imagination and logistical skills of Race Directors.
It can be on trail, coast, mountains, lakes or even towns and cities. At it's best swimrun is a dynamic and engaging adventure that can feel wild, primal, and often looks a bit silly."
(Mike Alexander, Founder of weswimrun.org)