Here's some very interesting information from Popular Science about what is on the so-called Dark Web, and parts of the general web which are not accessible to the masses...
There's some freaky stuff 'for sale' on the Dark Web. For example:
Dirty deeds done dirt cheap?
http://www.popsci.com/dark-web-revealed
It’s a place where online information is password protected, trapped behind paywalls, or requires special software to access--and it’s massive. By some estimates, it is 500 times larger than the surface Web that most people search every day. Yet it’s almost completely out of sight. According to a study published in Nature, Google indexes no more than 16 percent of the surface Web and misses all of the Deep Web. Any given search turns up just 0.03 percent of the information that exists online (one in 3,000 pages).
There's some freaky stuff 'for sale' on the Dark Web. For example:
Hitmen: Service providers—including a firm named for the H.P. Lovecraft monster C’thulhu—advertise "permanent solutions to common problems." For everything from private grudges to political assassinations, these hired guns accept bitcoin as payment and provide photographic proof of the deed.
Dirty deeds done dirt cheap?
http://www.popsci.com/dark-web-revealed