Saoirse

Saoirse is a mermaid who has lived in the deep lake at the base of the Grey Hawk Falls, though she rarely surfaces and has kept her existence secret from the villagers. She has been affected by poison in the water, meaning she now needs to surface to breathe fresh air some mornings, when she sings beautifully. She is incredibly shy, but seems to know a lot about the aquatic ecosystem.

It turns out that she was a Sea Hag in disguise, and has been dispatched by the party.