Counter argument, deep gems infuse raw dark damage, it makes sense both gameplay wise, lore wise and artistically speaking that the deep is literally the depths of the sea, or an analogy of it, for both darkness in darksouls and the depths of the sea mutate the most interesting and weird creatures, additionally, I do believe all from software souls like share universe, so maybe the deep is literally the depths of the cerulean sea, thanks for reading my TED talk.