Cleaning Sensor Ports Out?

I am taking a trip to Iceland next week. I want to use my i2 solar as much as possible!

If I soak my watch in water and am underwater for a while, do I need to clean the watch sensors out after I am done? I notice the small slit on the right side of the device which I am assuming is a sensor. I don't know where the other sensors are but I want to make my last watch and not destroy it. Yes I know it's 100ATM I am more worried about causing unneeded harm to the sensors.

Will the charging connections get rusty? I can't seem to find anything online explaining any of this.

Thank you!