I suppose it depends on what you consider swimming. I am PADI rescue certified, and I don't swim in the traditional sense. I dog paddle, float on my back, and can stay afloat while moving through the surface of the water at a reasonable speed. But I have yet to master the "Proper" swimming form. My question to the original poster is how do you get back to the boat or shore after a dive? Some of the tasks you will have to do is retrieve a diver at the surface, locate a missing diver bring them to the surface and tow them back to shore/boat. Remember that you have your BC, your victims have a BC and they should be inflated while at the surface, so as long as you can cover a distance at the surface, you should be fine.