Hi! This piece is really good, and I love the idea of drawing out what characters look like in roleplays, there are some things I would like to give suggestions on for improving your art and for future pieces.
The anatomy in this piece is really good, keep up the good work! However, I would like to suggest not making the breasts look too large (that's just my opinion ._.)
Second thing I would like to suggest is to try to draw your own backgrounds, which is going to take a bit of practice to get right. Backgrounds (especially ocean backgrounds) are a bit tough to master, but I highly recommend to look up reference pictures and getting some ideas for an underwater background.
Thirdly, (this has to do with lighting and shading) since you used a premade background (nothing wrong with that), there's an area where light is coming from somewhere on the right. Wherever light hits, there will always be shadows on whatever the light is hitting.
The bubbles are a nice touch, while (although I'm guilty of this too) underwater, bubbles don't always appear in the water. (Just an opinion ._.)
I hope that this helps, and I hope you have a wonderful day/evening!