[HIS EYES LIGHT UP. Someone wants to listen to him? He's so happy! He nods enthusiastically.]

I was trying to learn more about the monsters killing people in the sea. But when I looked, I didn't find any. I just saw the merman and he looked at me like he wanted me to follow him, so I did. Eventually, I got stopped by some sort of barrier. But just beyond, I could see a city underwater. It looked just like this one.

...That must be... where the one you met came from too? That city?