Stay away from the edge of icy cliffs.
Stay away from roaring water in flood. A guy here died because he went right up to the edge of a raging torrent to look at it. The bank caved in and took him with it. I never heard that they even found his body.
Sue 
That actually happened to me once.  I was 14, on a boy scout trip (a planned 10 day excursion. This was day 1).  Went to the edge of a river, on granite rock. Somehow slipped (was about a foot or 2 back).  Down I went into Class V (heck, it might have been X!) rapids.  Bounced off some rocks, smashed into one long enough to catch my breath, went off some small waterfalls (thought I broke my legs it hurt so bad)... somehow made it to the side (current? Luck? God?) and hauled my butt out of there. 
It was a pretty quite hike the rest of the day.