If you haven't seen this comic before: gunshowcomic.com/648
You might at least have seen the meme that has spawned from it.
I think this is the mermaid equivalent of that.
She's probably thinking "This is fine" right now, or at least trying to tell herself that. Though in a couple of hours or so it wont be fine anymore. And I think she'll have trouble getting out of that tank on her own.