By drips and weeps over thousands if not millions of years, beauty is created underground. Here in the subterranean world the moist air and mineral-rich water create castles, not in the sky, but in the caves of the National Park System.

Cave formations (speleothems) seen at Skyway Lake within the depths of Wind Cave, Wind Cave National Park / NPS file

There are sparkling white nodules, wafer-thin balloons, mineral straws, and slabs of bacon (well, at least it looks like bacon). These are the speleothems; the decorations of the underworld. They are fashioned over time by minerals deposited from water droplets dangling from ceilings, splashing to the floor, or simply carried on air currents and accumulated by chance in frost-like forms.

Traveler Founder and Editor-in-Chief Kurt Repanshek had the opportunity to tour Wind Cave at Wind Cave National Park, and Jewel Cave at Jewel Cave National Monument, both in South Dakota. He writes of his experiences in both caves, about these wonders created over time, and the significance of these two caves and their formations in this Feature Story.