Wow.
Hope you've recovered from the experience.
I've wondered for a while how deep the canal is, but never wanted to find out myself... now someone's done the research for me :)
Wouldn't have happened if I was wearing hi-viz
-- why not? How did this happen? I'm intrigued so it doesn't happen to me too!
The time I fell off my bike was by the canal. I was sober, it was night, and my front wheel some how wedged between two cobbles under one of the bridges, can't really explain how it happened. Was going really slowly anyway, so was no biggy. And I didn't end up in the water.
Anyway, good luck finding the glasses, maybe a fishing net might help? Or maybe you could recruit the kayakers.
I'm afraid I'm away for the week, so can't help with a search party, but minimoth might be able to lend a hand.
EDIT: Also, thanks for admitting the canal-experience on here :) I might have kept it quiet myself :D