Pretty lucky man. Lucky you had the patience for all that cos I know if it was me I would've just done it blind and worried about the problems as they arose in real time. Which by the sounds of this could have been a fatal decision.
I haven't done any go with the flow boating in drains. Nor have I had any near death experiences as I'd classify them. Most I can think of is falling down the manhole ladder in Great Staircase. I was pretty drunk and idk, just missed a rung and went straight down.
Cunningham Pier I was drinking on the litter trap and my leg slipped between it somehow. Opened a large gash just below the knee which required stitches and I could barely walk for a week, even with strong prescriptions. Ruined my Christmas holidays for sure
But I suppose we just all need to count our lucky stars sometimes. You can take every precaution in the world but in the type of unpredictable environments we often find ourselves in sometimes it doesn't matter regardless.
Stay safe out there.
Wander often. Wonder always.