Hello and welcome to HCM
In my opinion you must consult your surgeon whether the process of healing is complete or not. Healing is to be completed externally as well as internally because swimming in river require a lot of muscle work.
Usually the laparoscopic surgery
requires about 2 weeks for complete healing without any complication.
So its your surgery who can give you a better idea about the idea of swimming because he know what he has done and what kind of rest or work he can allow to you.