Short answer: probably not
Long answer: Oxbridge is academic focused, hence experiences unrelated to your subject of choice will unlikely catch their eye. Not that you can't mention your experience with swimming in your personal statement, but try and point out skills, lessons, etc that you've learnt from swimming that would make you a better student for that subject. However, I would prioritise experiences that are directly related first, and only mention this if there's still space. Hope this helps!