Below is a three dimensional flythrough illustration of the female reproductive organs. (It may take a few seconds to load). You can zoom in and out and spin the image around to view from any angle. This clearly shows the whole clitoris extending inside and enveloping the vagina. The clitoris is made from erectile tissue and is rich with sensitive nerve endings. As far as we are aware it is the only human organ that exists solely for the purpose of pleasure.
Amazingly the full extent of this vital part of the female anatomy was only properly disclosed in 2005.