The Drowning Mermaid

First of all, I love the twisted little ending. It's very human and real and exactly the sense of humor I grew up with from my parents, so I can relate to it precisely.

I love the story, many of the images, and I think you're headed in a nice direction. However, I think this needs some slicing and thinking through of tense. Specifically S3. This seems to be set up for a future tense "someday soon" then you go into a past perfect tense. It's not that it's terribly confusing, but I do think the shift is a bit awkward and dissipates some of the pop of the piece.

The opening stanza is an interesting quandry to me, due to the fact you're creating a real image but purposefully being deceptive with the words. "sat closed' is a nice way of talking about her eyes, but the feet in the sand butted up against it while interesting is every so slightly surreal and the poem goes in a more realistic direction, i think. I'm sure others will chime in on that. Personally, I think S1 is nice but i'm not sure it works in this context.

Again with the parenthetical in s2. It's interesting, but I'm not sure it fits there. I might suggest working it in more logically into the piece rather than blurting it out in that way.

two legs as one
held tightly together,

 Cases like that line, I'd rather see you work it more naturally, perhaps, "two legs held tightly together as one" or something like that. I think there's a general tendency here toward the indirect statements, where I'd like to see you keep your verbs as active and vibrant as possible.