Get a url for a site that isn’t registered on search engines. And if you do mean dark web and not deep web, either a special browser, settings, or password.
I have some experience with it, but probably not the kind you’re thinking of. Nothing horribly interesting. Most just server backend stuff, personal projects, etc.
As long as you’re not searching for child porn, classified government files, or downloading/ purchasing illegal goods and services, browsing is for sure legal, but might land you malware depending on the sites you’re on.