I've never been hiking in such extreme situations, but if in the situation in the question, i.e. you're hiking in very cold weather and someone falls in (let's say so pretty much their whole body is ...
If I'm alone in a survival situation and I have to cross a very cold river that's still flowing, how should I accomplish this safely?
When roaming the outdoors, it might happen that one finds oneself in a situation that is much, much colder than one planned for. What can one do in such an emergency, especially when it's so cold ...