How do you get protected by sharks when you are diving?

You don't get any protection, but they aren't interested in humans, we have far too many bones for them. They might be curious but it's highly unlikely that you'll see an aggressive shark whilst you're diving, mostly nurse sharks, reef sharks and, if you're lucky, a hammerhead, but they will teach you what to do if you do. Most sharks will avoid you, and if they do swim up to you then won't come close enough to harm you, so don't worry about it! It's actually an amazing experience to be so close to one, they're a lot nicer than you think!