Mystery Through The Unknown

You entered a competition which you need to complete numerous questions correct to win a prize. You are so close to winning something, not that you know what you're trying to win. How much of the Blue Mountains hasn't been discovered? Then you remembered that you checked it on a website a couple weeks ago. "What was it?" You thought to yourself. A minute later you remembered the answer was that the amount of square km was 6km times 7km.