How to Apply Underwater Shader Only Below Water Level in Unity Shader Graph?

Hi everyone,
I want to make an underwater shader graph, I already have a prototype but when my player enters the water (mesh with another shader graph applied) the underwater shader graph is applied to the entire screen, but I wanted it to be applied only to the areas there are below the water plane, and only apply on the entire screen if he is entirely underwater.
I saw a video where a guy explains how he did this but doesn’t show exactly how to do it, and as I’m a beginner I don’t know how to do it in the shader graph, can anyone help me do this?
Skip to 7:53 and it will start explaining exactly what I want to do

There is also an asset on the Asset Store that does this exact thing, so I know it’s possible.

I just found a video of a guy doing it with code. I haven’t tested it yet, but I’m looking forward to a solution with Shader Graph.

I would be very interested in this too, sounds like nobody gonna reply here who knows :frowning: