Ok being immortal means not aging. Calypso can DIE, just not of old age or internal deterioration. So no for the "can go as deep as she wants" but the rest is worthy>>> slight ToA spoilers but no, she can't do any martial arts
The official art is just horrible, this picture of Nico being the absolute worst. Aside from the fact this art looks hideous, that's not even how he's described in the book. I like to think of Burdge's and Viria's art as the official fandom art.
(Actually tear in my heart is in the middle they go in order from the heavydirtysoul to goner, left to right)<< tear in my heart is supposed to be the only one not touched by the red(fear/insecurities )