Link/Redirect

I’ve tried searching the forums but I don’t really get or can find the specific solution to my problem. It’s simple really, here is what I want to happen:

I want to create a page which, of course, will be included in the main navigation. But this is no ordinary page, for it is only “link” or it redirects towards another page outside of the WP CMS, like a wiki or something.

So that’s all. Thanks!