You're all so funny!
I would have loved to soak in warm water! We did hit one hot spring and that helped but there were just sooo many spines! I literally suffered for months.
I had to keep my mouth shut and not whine because the surest way to ruin a good river trip is to have a whiner on it and I was with a bunch of guys who would have tortured me more than the cactus did.
I found a picture of the cactus but there was no name attached to the pic so I am no closer to ID. Maybe someone will recognize it from the picture.