Blue Hole (Red Sea)
The Blue Hole is a diving location on the southeast Sinai, a few kilometres north of Dahab, Egypt on the coast of the Red Sea.
Blue Mountains (New South Wales)
Following European settlement of the Sydney area, the area was named the "Carmarthen and Lansdowne Hills" by Arthur Phillip in 1788. The Carmarthen Hills were in the north of the region and the Lansdowne Hills were in the south. The name "Blue Mountains", however, was preferred and is derived from the blue tinge the range takes on when viewed from a distance. The tinge is believed to be caused by Mie scattering which occurs when incoming light with shorter wavelengths is preferentially scattered by particles within the atmosphere imparting a blue-greyish colour to any distant objects, including mountains and clouds. Volatile terpenoids emitted in large quantities by the abundant eucalyptus trees in the Blue Mountains may cause Mie scattering and thus the blue haze for which the mountains were named.