Meh.
The idea behind the "Deep Web" is a rather outdated one. Allow me to explain why. When the term "Deep Web" first came out, it was during a time when the Internet was novel, not as popular, and when search engines absolutely sucked for finding information. The whole idea behind the "Deep Web" was that, because the tools to find information online was not as easy and intuitive, few people would actually bother to go very far in finding info. To be honest, having been on the Internet through that time, it isn't hard to see why that was a fascinating and truthful idea. In the 1990s and early 2000s, the Internet genuinely seemed like a huge untapped resource of information. This is especially true when search engines made it difficult to find info, and when Internet speeds forced you to wait upwards of 10 minutes for a single page to load.
Why was this "untapped resource of information" fascinating enough that it led people to term it the "Deep Web"? Well, you should all know this by now, but if you can imagine it there is probably someplace that looks at it and discusses it, and even encourages it. There should be communities for everything legal and illegal, disturbuing and creepy, powerful and crazy, naughty and nice. Whatever you imagine, whether it's hacker supergroups, communities dedicated to weird violent or sexual fetishes, communities organizing terrorist acts and spreading propaganda, a knitting group for grandmas, databases of books galore, or places where you can sell things on a blackmarket... it exists out there. And, in large part, if it's not a very popular website or service, then it's probably a lot more specific to a certain issue or topic. This is a no brainer, and this shouldn't be new to you. As more people have used the Internet over the years, and search engines are smarter and better, much of this info has leaked out and become more "popularized". If you are truly keen you can find just about anything if you search enough for it or use the many software programs out there to find it... it's not as mysterious or secret as the OP would like you to believe.
Oddly enough, just like how Usenet, or Torrents work, or even DC++/Soulseek, what PostMetalActivist wont tell you in his OP is that the whole modern concept of a "Deep Web" can be accessed through a simple program, too:
https://www.torproject.org/ Over time, what has been termed the present "Deep Web" is - at the heart of it - centered on anonymous surfing of the net, and this has been perpetuated by groups like Anonymous, and other groups who may want to do things which are terribly illegal if made more publically known. It shouldn't be surprising that people who are doing illegal things want to keep their activities anonymous, or that people who want to start secret, select communities try hard to make their websites unsearchable by the less-than-desirable masses. It doesn't tend to succeed all too well, not as the Internet is getting more and more prolific and the ability to find things becomes easier and more dispersed. There's a certain mystique in this idea of a "hidden internet" full of dastardly individuals ready to take down the world, but if I can go on Reddit and read on the Frontpage that these activities are going on and how to get involved in that, that helps to prove the "hidden internet" is a fallacy. If you want to see gore, you can find it. If you want to know what Al-Qaeda is doing, oddly enough there's websites on that. The fact is most people don't want to, or don't care, and the "surface" Internet we live with is more than enough to live on.
I will say this. It's not the topic of this thread which is rather "inappropriate." I don't care if people wish to talk about how the Internet operates. But I will say this, PostMetalActivist. The whole idea of you coming around here and saying "check this out, but don't tell anyone else" really shows your age.