I had open surgery to repair a right inguinal hernia just under 4 weeks ago - so i'm still trying to figure out what exercises I can and can't do.
- walking : good.
- gentle cycling : that was a mistake! Caused the sensation of pressure I had before the surgery to return! I stopped this immediately and won't try again for a few more weeks. Luckily it seems to have subsided since then. Fingers crossed it hasn't caused any lasting damage.
- gentle swimming : this was great, will do more of this. I was able to push quite a bit harder than I had expected too.

re swimming: I read somewhere the water equalizes the internal abdominal pressure, making it less risky than other types of cardio exercise for hernia recovery. But, i'd advise you to do your own research here rather than taking my word for it.