https://mythus.fandom.com/wiki/Illhveli
A very, very unfinished illhveli page!
Awesome! That's the first step! Thanks for taking the initiative!
UPDATE: I have no idea what else to say about them. please help.
I'm going to continue looking for valid sources. It looks like not a lot about them has been translated to English. In the meantime I found this interesting article which talks about the different types:
https://mediachomp.com/icelands-evil-whales-who-shall-not-be-named/?fbclid=IwAR2XQycYRznlUZPjq57WM3I2_qCLnfEDT8f0PoZTz5QqBvNdOhfrABUk9cQ
What do you think?