All 2D animation is put into Maya on a plane, which cast the shadow and reflects the light.
There will be four shots of the girl on a boat, showing time lapse, that means that she swims far and for quite a while and only then she sees this massive mysterious entrance to somewhere coming out from the fog.
This needs colour correction, more reds and oranges in the sky.

Here the ghost will flash in the window and camera will slowly moving forward, dissolving to the shot inside the window.