In the sunken ruins I pick up the music box and got the mermaid tf I also had picked up the deep sea pearl earlier so there was a sparkle and I interacted with it and got the sea monster tf, I was then teleported back up the the first room so I went back down the stairs having not completed the mermaid quest the stairs back up was blocked and I could not use the dive ability that the mermaid form has so I was unable to reinter the water. (Note: I save every time I come across a save point so I have a save that I can go back to, thanks any way.)