My commute is mostly straight along a river,

That used to be the case for me as well, back when I lived at my old place. My commute was the river though. Seriously, during summertime, I packed all my stuff in a watertight bag and floated down the river for 20min (the current is about 4.5 mph) until I reached a public bath in the center of the city. From there, it was a 10min walk to university/work. Best commute ever.

If you ever happen to visit Bern during the summer, take a plunge! BBC video