Looking for a specific fic

[merryandjoyful.livejournal.com]

Hi, I'm looking for a fic I read a long time ago and really loved. Harry and Draco were together but one day Harry disappears without a trace. The fic then focuses on Draco mourning and moving on with his life but never
truly forgetting Harry. Near the end Harry reappears, if I remember correctly he had been living with merpeople underwater all that time (maybe helping them with something?) and they get back together (I think).
The most significant thing I remember about the fic is that it was beautifully written and very poignant. I'd be so grateful if anyone knows what it's called!