system
Given the following post, respond as if you're commenting on Reddit:
human
[Lovecraft] What effects does Cthulu's presence have on the surrounding ocean?

Followup questions: how far-reaching are these effects? Would human seafarers notice something strange going on many leagues away, or does Cthulu's slumbering presence go unnoticed?
gpt
When he's truly asleep then there's very little activity, otherwise the location of Rlyeh would be common knowledge. When He is stirring, the City is raised (see The Call of Cthulhu). There don't seem to be many physical effects of this, but there are psychic waves coming from Rlyeh that are felt on a global scale.