To cross a river in the Brooks Range you either have to go around it at the headwaters if it's not too far, wade it if it's not too deep, raft it if you have a raft or can build one, or swim it. On the Sheenjek River, I had to swim it towing my pack on a willow branch raft to get across, with my dog swimming back and forth wondering which side I was heading for since I was crossing so slow. Being a hundred miles from the nearst village, I couldn't afford to lose my gear in the river or get my food wet, or I wouldn't be able to hike out. So I was very worried. I got to say it was pretty chilly - my feet and hands were going numb.