My story has a water nymph in it. She is around 17 and fairly tall but delicate. Her name is Thalassa Pari. She is training to be able to protect a lake (like all nymphs and her uncle). I was thinking of having her with long, wavy hair but if you have another idea let me know. Thanks, if you need some more description I’ll add more.
Maybe a pale baby blue?
I have some ideas! The first colour that comes to my mind is a mint green or sea foam (#BAF8CC), or even like a deep blue to light green ombre. But if you're looking for a more natural colour, I could see her with a nice platinum blonde! I hope this helps!
White? Or really pastel pink?
green hair so it blends in with underwater plants or even just a cyan kind of turquoise colour.
cornflower blue
Don't do a light blue. For a Limnades, I'd say either a deep aqua colour (#145E58 [hexcode]), a deep cyan colour (#1D7479) or if you want to avoid stereotypical colours, perhaps a sandy blonde?
light ish red
I wouldn't do darker colors, because they wouldn't stand out much in the water. It makes them more aesthetically pleasing if their hair is lighter than their skin (in my opinion at least, but I'm no expert)
I'd say it depends on how close to human you're making her and on her environment. Is she supposed to stand out? Or is she supposed to blend in? Also remember that hair gets darker when it's wet, so if she had light brown hair it would look dark in the water. If she's not supposed to be very close to human, what about translucent? Like polar bear fur. Aesthetically I think it would be cool if a water nymph had hair that literally looked like water. As a side note, long hair is hard to fight with unless you're really good because opponents can take advantage of it- like grabbing/pulling it in a fight, or getting it caught on something. If you want to keep her hair long, I'd suggest having her braid it or something to keep it out of her way.