Did a new years trip on the Rio Grande through Big Bend many years ago; very nice, class 2-3.
Hit a blizzard and camped next to a natural hot spring; spent a day sitting in it with only our heads and a beer laden hand exposed while 6" of snow covered everything.
The next day saw Federal es riding our way (really, on horses!) as we were packing up; made a quick and strategic withdrawal to the US side of the river, cause, you know, we had a whammy can full of..........things the Federal es would have confiscated, along with us and our gear.
That was a great adventure!