Skinny Dip is a standalone illustration by Iron Eater. It ran in Issue 51 at http://s2b2.livejournal.com/289119.html, and is mirrored at http://www.shousetsubangbang.com/mirror/skinny-dip.
This piece was made entirely in Clip Studio Paint/Manga Studio 5, save for an initial scanned pencil sketch. It makes gratuitous use of the lasso tool and about a bazillion layers.
I knew more or less what I wanted to do with this image shortly after deciding that I was going to illustrate something for the Under the Sea issue, and while it took a false start or two the composition came together very quickly. Being October, the slightly darker implications have a good home, though I was originally unsure if it was a bit much for what's ultimately a pretty cheerful zine; one letter to the editor later I was merrily plotting out murderous lure-mermen.
Never underestimate the value of checking in with your editor.
For the record, I figure the aquatic fella is a complete entity (that is, his top and bottom parts don't have different personalities or anything), and he might be a little sensitive about the whole "man-eating gay monster" thing. Being stuck in a lake gets very lonely.