Do go into the water! Original post here.

Sourced to FUCK YEAH MONSTER GIRLS via dmaestro. Original text:

Explore.

Bonus Image Provenance: I commissioned Bacchus at ErosBlog to research this image further, and he has come up with the following additional details.

This image stream on Tumblr originated here:

http://fuckyeahmonstergirls.tumblr.com/post/4677348347

Surprisingly for Tumblr, at that location there is a rare “source” attribution to this URL:

http://monster-girl.homelinux.net/up/No_2783.png

That .png is 20 pixels wider than all the tumblr versions, and is the highest-resolution image on the net. With a little exploring of directories, we learn that it’s at the “Monster-Girls Uploader” site:

http://monster-girl.homelinux.net/

It’s actually linked from this page, where we can see it was uploaded in 2007:

http://monster-girl.homelinux.net/upload.cgi?page=87&lm=40&sort=&rev=&lang=en

It’s identified (captioned?) there with these characters: [Editor’s note: unfortunately the characters didn’t survive transmission]

Google translate identifies this as the Japanese word for Dagon, which I’m taking for the image title (lacking any other candidates). The English-language Wikpedia entry for “Dagon” identifies an ancient (~2500 BC) Mesopatomian god of both fish and fertility, sometimes drawn as a mer-man in more modern sources:

http://en.wikipedia.org/wiki/Dagon
http://en.wikipedia.org/wiki/File:Dagon1.jpg

The autotranslated Japanese wikipedia entry for Dagon offers us the additional tidbit — likely relevant to this image — that Dagon features in the Cthulu mythos as the founder of a half-fish, half-human deep sea cult. It’s no great leap to imagine that your friendly Dagon-girl is recruiting!

http://translate.google.com/translate?hl=en&sl=ja&u=http://ja.wikipedia.org/wiki/???&prev=/search%3Fq%3D%25E3%2583%2580%25E3%2582%25B4%25E3%2583%25B3%26client%3Dfirefox-a%26hs%3D0Du%26rls%3Dorg.mozilla:en-US:official

Searching further, I discover your image on Danbooru (uploaded in 2008 or prior) with a tag for the artist name of “ze (sawakihein)”:

http://danbooru.donmai.us/posts/182341

That tag is a hyperlink that takes us to several pages of additional artwork with the same nametag:

http://danbooru.donmai.us/posts?tags=ze_%28sawakihein%29

Notable and potentially of interest among these is a frog girl and tadpole sidekick:

http://danbooru.donmai.us/posts/309653?tags=ze_%28sawakihein%29

I was unable to develop any English-language information about this artist, but I was able to turn up two similar galleries that substantially overlap the content for this artist at Danbooru:

http://rule34.xxx/index.php?page=post&s=list&tags=ze_%28sawakihein%29
http://chan.sankakucomplex.com/wiki/show?title=ze_%28sawakihein%29

Bacchus is actively taking image research commissions, and if you have adult imagery you’re curious to learn more about, I encourage you to visit Bacchus’s introductory post for his image-searching service, where you can find details about how to commission him.