So, I intend to film my hand moving forward to the water.  The entrance is important to the effect and I envision an exaggerated springing in, as if pressing on plastic food wrap, before it pushes through, then sort of popping back.
do you have a visual reference you can point us to? If i think of putting my finger in a glass of water, I imagine some optical distortion and refraction, but not much else.
Simple question, not sure a simple answer. I'd like to make an effect that would appear as if I were pressing my finger through a wall of water. Envision a wall of water facing you, hand pushes straight in, slight angle, index finger extended, and just pushing the index finger through the wall of water.
It's that entry part that is the real question. The wall of water will have enough color to show a difference with a bright green hue (think The Shape of Water because that's basically what I'm doing). As the finger goes through, naturally, it will then change to the color of the water to indicate it is within the water.
The entry, a springiness to it, that kind of thing is what I'm trying to achieve.