Travertines, or calcium deposits, made by hot mineral-laden waters at Pamukkale, near Denizli in Meander River valley of Turkeys Aegean region. Note the people walking on the puffy-looking clouds of brilliant stone. This is an old photo. The travertines have wisely been closed to strollers and bathers in order to preserve them. But you can still look! As for swimming, lots of modern pools at hotels allow you to splash in the naturally-warm, calcium-laden waters.