We were moored on the Coventry canal a few years ago, middle of the day sheltering from the rain and wind, a trad narrowboat went past us with large dog on back, the steerer all wrapped up in his rainwear. Dog falls off the back into canal and the steerer did not spot it, the dog swam to the side, couldn't get out because of the piling.
I ran down to drag the dog out, shouting at the guy to attract his attention. He did hear me eventually and they were reunited but it could have been very different.