There was some person on the conspiracy subreddit a few years back that claimed they worked for some part of the government. They said that all the world governments are aware that there's another entity that lives in our oceans, that they have their own cities, more advanced tech, and they're the "aliens" we hear about. They come from the oceans to observe us occasionally but we don't know why. If we mess with them, they easily destroy our stuff, so we all just leave them alone.

Not a true believer of random internet posts, I just think non-political conspiracies are fun to think about.