oceanScene

Copies the colour and depth of everything drawn behind the water into textures the ocean surface material can sample.

A surface shader cannot bind the frame's own depth buffer or colour target while drawing into them, and the water needs both: depth gives the length of the water column, and colour is what refraction bends and what screen-space reflections march through.

Both copies run at afterOpaque and are published through ~.modules.oceanScene, which is where the ocean materials pick them up.