National Nature Reserve SOOS
When you first step off the wooden boardwalk onto the dazzlingly white plain, you feel as though you've ended up somewhere completely different than in western Bohemia, yet you're only about 10 minutes' drive from the Sport-Relax Buky resort. Cracked crust, no trees, just the occasional clump of reeds — and all around, bubbling puddles from which gas bubbles escape with a quiet smack. The SOOS National Nature Reserve near Františkovy Lázně truly deserves its nickname "lunar landscape."
The Bottom of a Dried-Up Lake
That white surface is neither snow nor salt. It's a diatomite shield — a deposit of microscopic shells from diatoms, single-celled algae that lived in a shallow salt lake here roughly ten thousand years ago. When the lake dried up, it left behind meters of diatomite. Wind and water cracked it into slabs that today resemble a cracked clay bowl.
But nothing has settled beneath it all. The Cheb Basin lies in a geologically restless region — the earthquake swarms near Nový Kostel here are among the most closely monitored in Europe — and the earth's crust is so thin that gases from the depths seep through it.
Mofettes: Muddy Volcanoes Without Fire
SOOS's most famous attractions are mofettes — dry and muddy emissions of carbon dioxide. Where gas penetrates water-saturated mud, a "mud volcano" forms — a crater several tens of centimeters in diameter from which bubbles constantly rise. This isn't volcanic activity in the true sense; it's an echo of young volcanism, the same process that created nearby Komorní and Železná Hůrka.
The gas emerging from the mofettes is overwhelmingly pure carbon dioxide. Because it's heavier than air, it stays close to the ground in depressions — and that's precisely why it's really not worth stepping off the boardwalk. For small animals, this sometimes proves fatal.
A Salt Marsh in the Heart of Bohemia
The mineral springs that emerge here carry dissolved salts. This creates something completely unexpected: an inland salt marsh, a habitat typically found on seashores. Glasswort and other halophytic species grow here — plants you practically won't find elsewhere inland.
A few dozen meters further, the landscape transforms into a peat bog with bog myrtle, hoary pepperbush, buckbean, and carnivorous sundew. In just one kilometer of the nature trail, you pass through three worlds that normally shouldn't meet. It was precisely this improbable mosaic that led to the reserve being declared in 1964.
What You'll See Besides the Mud
The area is more than just a trail. You'll find:
• A natural history museum with exhibits on the geology of the Cheb Basin, seismicity, and the history of local mineral waters
• A paleontology exhibit with life-sized models of prehistoric reptiles — usually the main reason children want to come back
• A rescue station for disabled animals, where injured birds of prey, owls, and other animals that can no longer return to the wild spend their final days
Birdwatchers come here for the wetland avifauna — with a bit of luck, you might spot a snipe or hear the call of cranes.
Practical Tips
SOOS is located about 6 km northeast of Františkovy Lázně near the village of Nový Drahov; it's a short drive by car, but you can also cycle here along marked trails from the spa town. The trail is short and wooden-boarded, manageable even for preschoolers, though strollers and wheelchairs struggle on the boardwalk.
Spring or late autumn is ideal — cool air above the mofettes makes the vapors visible, and the white plain looks most dramatic in slanting light. In summer, on the other hand, expect mosquitoes and sharp glare from the diatomite; sunglasses aren't unnecessary.
The area operates seasonally, roughly from April to October. It's best to check opening hours and admission prices before your visit — if you'd like, I can look up current information.