The only time one would have a ‘hole’ in water is when there was something just stuck in the water (like an oar, or maybe someone walking through the water.) If an item was in the water for some time, there would actually be a slight rise up the item at the point of contact between the water and the item (forget the name of the effect but related to surface tension.) This second effect, the slight rise would be so small it would only be visible on very extreme closeups of the contact between the water and item, ie… not an issue for anything but the rarest case.
I was trying to remember the name of that effect as well, and Google provided no help. You can really see it if you look at a glass of water at eye level. As for the hole, what you describe is exactly what we were discussing. The only reason I mentioned it to Hellboy is because it was difficult to see the waterline against the post in the water, but his changes seemed to address that very well. IMO
I believe the term you are looking for is meniscus, formed by the surface tension.