For air travel I am using German made Koenig photo bags. He has pre-defined sets or produces them up to your requirements. The backpack is entirely waterproof, so you can even put them in the water (not too sure why you would wish to do this ...). You would find it here: https://www.koenig-photobags.de/ (I have no interests whatsoever in this brand).
I own three inlets, so I can switch according to the trip planned.
I own three inlets, so I can switch according to the trip planned.