The Blue Mountains is one of the major destinations and a must see icon for tourists visiting Sydney. I have been here when i visited Sydney the first time. No matter how often you go there, there will always be something to see, do, experience and explore in that vast area. The first feeling is awe, grand, spectacular, then trying to sample the smaller details eventually will make the visitors feel more awe, more grand, more spectacular. I think the feeling gets bigger as you try and explore the smaller details. Here those smaller details are endless.
Blue mountains gets its name from the blue haze as you look further to the horizon. That blue color has a very scientific explanation because the eucalyptus trees fully vegetating the area produced oils that react to the sun's light producing the much obvious blue color. But of course, there is still the explanation from the color spectrum where other colors are absorbed, while blue is reflected.