Travel deep dive
Bohemia's Springs and Sandstone: One Geology, Two Landscapes
The elegant spa towns of the Bohemian interior and the sandstone wilderness near the German border read as two completely different sides of Czechia — aristocratic colonnades against raw rock formations — but both are expressions of the same underlying geology. Bohemia's sedimentary bedrock is porous and fractured in ways that let deep, mineral-rich water rise to the surface in one region and let surface water and wind carve dramatic shapes out of exposed rock in another, the same basic material behaving completely differently depending on what's happening to it.
Updated 2026-08-15
Why Karlovy Vary's water comes out hot and mineral-rich
Karlovy Vary's springs — the town holds 13 main ones, reaching temperatures up to 72°C — exist because rainwater seeps deep into fractured bedrock, is heated by the Earth's natural underground temperature gradient, and picks up dissolved minerals from the rock it passes through before rising back to the surface along fault lines that give it a route upward. That combination of depth, heat and mineral content is what 18th-century European aristocracy came specifically to drink and bathe in, taken traditionally from porcelain spa cups while promenading beneath the town's elegant colonnades — a ritual built entirely around a geological accident of how deep the water travelled and what it dissolved along the way.
Karlovy Vary, Mariánské Lázně and Františkovy Lázně — collectively the Spa Triangle, UNESCO-listed since 2021 — each draw on the same underlying mineral-spring geology but produce genuinely different water chemistry depending on the specific rock layers each town's springs pass through, which is part of why spa traditions historically prescribed different towns for different ailments rather than treating the three as interchangeable.
Bohemian Switzerland: the same rock, eroding instead of flowing
Bohemian Switzerland National Park, on the German border, sits on sandstone laid down as sediment roughly 90 million years ago, later uplifted and exposed to millions of years of wind and water erosion that carved the park's characteristic rock towers, narrow gorges and table-like formations. The Pravčická Gate, the largest natural sandstone arch in Europe, formed through the same erosion process acting on a specific weakness in the rock — water and wind exploited a fracture in the sandstone over an immense span of time, gradually widening it into the open arch visible today rather than leaving a solid rock face.
That's the same fundamental process — water working on porous, fractured Bohemian rock over long timescales — that produces Karlovy Vary's hot springs elsewhere in the region, just with the water moving downward and outward through erosion here rather than upward and inward through mineral-rich circulation there. Two landscapes that look nothing alike, produced by variations on the same basic geological mechanism.
Visiting both: a genuine contrast within one country
The Spa Triangle towns and Bohemian Switzerland sit close enough to each other in the country's northwest that combining both into a single trip beyond Prague is genuinely practical, and the contrast between them is part of the appeal — a day spent promenading through Karlovy Vary's Habsburg-era elegance followed by a day hiking beneath sandstone towers offers two completely different registers of the same regional geology. Karlovy Vary's film festival each July adds a modern cultural layer to the older spa-town identity, while Bohemian Switzerland remains genuinely wild hiking country with marked trails through the park's rock formations and gorges.