Although I travel earlier than most, predawn, to a hunting position, I once found another hunting party already in my intended position. I walked further down, into an unfamiliar area.
While walking through about 25 yards of cattails, I stepped into a bottomless hole between the cattail that was only slightly as big around as I was. I went right down and bobbed right back up with enough buoyancy & momentum to step out of the hole on my knees.
There was no moon and I could not believe how stupid I had been. I was wearing a full life jacket, so when I fell into this bottomless column of icy water, I was shot back out. What a miracle.