In Netflix's Kipo, the scenes where she mutated and lost control, it shows Kipo standing in a place that seems to consist of shallow water, but nothing to the horizon. Sometimes able to look out into the world, other times able to see the Jaguar she's mutated into.
This seems to have strong parallels with Naruto, where when he interacts with the nine-tailed fox imprisoned in his body, it also shows this happening with both him and the fox standing in shallow water.
Both those cases are about there being two "beings" in one body, and representing an internal world where either one goes when the other is in control, or where they communicate.
But there are similar instances in other places too. In Stranger Things, for example, when Eleven reaches out to spy on people, it's depicted in a very similar way: Shallow water and nothing except the two subjects.
I think this is also similar to the Soulworld in the MCU. Whenever anyone obtains or uses the soul stone, we see them in a place that is shallow water to the horizon.
Is there some cultural origin to this imagery?