Fantasy books centered around merfolk

Heyo!

It's my first time posting here (and in other subreddits of that type xD), so I hope I'm doing this correctly

I'd love some recommendations for fantasy books about merfolk, specifically sirens would be amazing. Pirates are also cool ^{^}

Not all too dark, and I'd love if it wasn't centered around romance; I don't mind romance being in there, but I'm not too fond of it

No smut at all, please!

Thank you so much!