A number of years ago, I hiked up to Camp Shurman with some friends. There were four of us: myself and my friend Fred, who had glacier experience, and a guy from Fred’s work and the guy’s wife or girlfriend (I forget which) who had no experience. We roped up hiking over the Interglacier, despite the dozens of other folks we saw not roped up. Lunch at Camp Shurman, then headed down, and decided not to rope up, because travelling roped with inexperienced people is frustrating, and anyhow, it’s a “dead” glacier, right?
We were nearly across the glacier, a hundred feet from rock when, right ahead of me, Fred punched through into a crevasse, his rope securely stowed in his pack. He instinctively caught himself by his elbows, and his feet were dangling, he said later, over what looked like a very deep hole.
I was just a few feet behind him; I plopped down on my butt with my feet in front of me to brace myself, and reached my ice axe out to him. He grabbed it and I pulled him out, the other guy (I don’t remember his name) pulling on my back.
It wasn’t wasn't until the adrenaline rush subsided that I grasped just how horrible that could have been. We had no rope: it was in his pack. There weren’t very many others around by that time, as I recall there were only a few folks off in the distance.
Overall, a cheap lesson not to screw around with glacier safety.