A marble marvel

It'll take a boat ride across a mountain-ringed glacial lake to get this view of Chile's Cuevas de Marmol, or Marble Caves. From our photo you might guess this is a vast, gaping cavern. In reality, though, you may have to duck as your boat passes under its low-slung stone ceilings. Reflecting blue hues from the glacial waters, the swirling patterns of the cavern walls have been revealed over the past 6,000 years as waves carved these marbled maws into the lakeside cliffs.