This is Namorita. She's related somehow to Namor, the Submariner. I don't recall the nature of their relationship, and I don't care enough to research it. It's part of a series of erotic athletic drawings I've been doing, actually, since I got into superheroes as an adolescent. I discovered drawing superheroes was a way to draw nudes without getting in whatever trouble one might get into for drawing nudes.
My recent evolution/revelation/realization is that I don't have to draw superheroes anymore to draw heroic, athletic nude figures. In a way, today's drawing of Namorita is a throwback to my older aesthetic strategy, but I decided to run with it in this case. As it happens, I actually like this character, remembered fondly from Bill Everett's brief, early 70's stint on The Submariner.