Although adventure racing is a multidiscipine sport, swimming is rarely included; well, not a swim of any significant distance. Sure, you see adventure racers in YouTube videos swimming – but they’re probably swimming less than 200m – with their backpacks – to cross a small dam or river.
It seems that many people new to this sport are concerned about the ‘swimming component’ in adventure racing. Upfront – we rarely swim; this isn’t triathlon. And when we do, it is usually to cross a small dam or a river. Not ‘proper swimming’. Distances are usually short – like <200m and we’ve usually got backpacks to swim with too. We’ve even swum with bicycles across rivers! Swimming in adventure racing is often more doggy paddle than freestyle.
Race organisers will let you pre-race if you have to swim; and they’ll usually mention the distance – like 500m.
Some international events have had a bigger swimming component, like the 2009 Abu Dhabi Adventure Challenge, which had a swim of 1km in the prologue. Race organisation transported backpacks and they allowed participants to use goggles and floatation, if desired.
Don’t stress about swimming in adventure racing (rather practise your navigation!). But, that said, for your own safety and that of your teammates with any water discipline (kayaking, rafting, river crossings, tubing etc), you should be a competent swimmer.