Silberen Karst Loop from Pragelpass: Walking on the Moon

Have you ever wanted to leave Earth without actually going to another planet? Nestled high in the Schwyzer Alps, the Karstspur Silberen loop on the Pragelpass delivers an experience that feels less like normal trekking and more like a space walk across the surface of the moon.

This 12.5 km loop takes you through Switzerland’s largest limestone karst field, demanding hours of focused footwork. So grab your toughest hiking boots, we're exploring one of the most surreal geological anomalies and storied mountain passes in Europe…

Route at a Glance

• Distance: 12.5 km (Standard Circular path - either left or right)

• Elevation Gain/Loss: +/-730m (R) +/-860m (L)

• Time: ~4 to 5 hours

• Difficulty: T3 Hard / Technical & Steep 

• Start/End Point: Pragelpass Ost Parking (1,548 m) - can be done in either direction

Best Time of Year

Because of its high-alpine environment and the complex geological terrain, the hiking season for the Silberen loop is relatively short:

• Peak Window: Late July to early Oct. is the prime window to attempt this route. By late July, the winter & spring snow accumulation has usually melted off the lower trails, making route finding safer - see below.

• Golden Rule: Start Early: Because of the technical terrain, a 3-4h hike can easily stretch to 5+ hours if you take your time calculating steps, going off trail, taking photos, etc. Starting early ensures you complete the most intense sections before it gets too hot, and gives you a comfortable safety buffer before sunset.

Hydration/Fuel Rule

Before you zip up your backpack, there are a few things you should prepare for:

• No Natural Water Sources: Because limestone acts like a giant, porous sieve, rainwater drains down into the mountain almost instantly. There are no alpine streams, no glacial rivers, and no small lakes anywhere on the upper trail.

• Intense Sun Reflection: Once you leave the green meadows of Alp Butzen, you are entirely exposed to the elements. There is no tree canopy or shade on the plateau. The white limestone rocks act like a giant solar mirror, reflecting heat and UV rays straight back at you - consider bringing UV/polarizing sunglasses.

• Pack Accordingly: You should carry at least 2.5 to 3 liters of water per person. Pack plenty of high-energy snacks (nuts, dried fruit, energy bars) to keep your focus sharp - navigating the broken terrain requires continuous, tiring mental concentration…

History of the Pragelpass

Before modern hiking routes, the Pragelpass (1,548 m) was a vital artery of Central Switzerland. Rather than an ordinary road, you are stepping onto an ancient trade path used since antiquity to move goods and settle alpine border disputes between the Cantons of Schwyz and Glarus.

The pass's most dramatic moment was in Sept. 1799 during the Napoleonic Wars. The legendary Russian General Alexander Suvorov was forced into a grueling strategic retreat across the Swiss Alps. After raging battles with the French down in the Muotathal valley, Suvorov marched 15,000 cold, exhausted, and starving Russian troops straight up over the rugged terrain of the Pragelpass toward Glarus. 

Today, your trek retraces part of this iconic Via Suvorov cultural hiking trail - see my other article on this topic…

Science Corner: How a Mountain Became a Moonscape

To truly appreciate the Silberen loop, you have to look down at the ground. You aren’t just hiking over random boulders; you are walking across a massive block of pure Schrattenkalk limestone:

• Glacial "Shave": Unlike its jagged, pointy neighbors like the Glärnisch massif, Silberen is remarkably flat and slab-like. During the last Ice Age, a colossal sheet of moving ice - the Muota glacier - buried this region. Its grinding weight acted like a giant razor, shearing off the peaks and planing the top of the mountain down into a horizontal plateau.

• Chemical Erosion: When the ice melted, rain mixed with atmospheric carbon dioxide to form a weak carbonic acid. This acidic water dissolved the bare stone over millennia, etching out Karren (flat rock pavements) & Grikes (deep, narrow fissures).

• Roof of a Hidden World: This surface process carved out the massive, dark void directly beneath your feet: the Hölloch, a sprawling subterranean labyrinth stretching over 200 Km, making it one of the longest cave systems on Earth! See my other article on this.

Phase 1: Leaving the Green World Behind

The journey begins at a windswept pass. The first two kilometers look like a quintessential postcard version of Switzerland. You will climb a steady, steep gradient (cranking up to a tough 33% at its sharpest!) past the idyllic green valley of Alp Butzen. Enjoy the soft grass and the rhythmic melody of cowbells while you can—it won't last long…

Phase 2: Walking the Silver Moonscape

Suddenly, you step out onto the plateau, and the greenery vanishes. Before you lies an oceanic expanse of blindingly white, deeply fissured rock platforms. Every single step here requires 100% concentration. Look westward over your shoulder during the climb - you'll catch great views of the Hoch-Ybrig ridge and its dramatic crests like the Drusberg and Forstberg framing the horizon.

Phase 3: Silberen Summit Reward

Pushing through the labyrinth of rock brings you to the broad ridge and the final destination: the Silberen/Twärenen summit at 2,320m. Standing by the landmark summit cross, you are treated to a jaw-dropping, layer-cake panorama:

• Fjord View: Peer directly over the eastern cliffside to look straight down into the chasm holding the brilliant, deep blue waters of Lake Klöntal (Klöntalersee).

• Glärnisch Massif: Looming directly across the lake valley is the massive, heavily glaciated wall of the Glärnisch Massif.

• Endless Horizons: Spin around 360 degrees to spot the jagged, iconic spikes of the Glarus and Uri Alps, stretching all the way across Central Switzerland to the distant peak of the Säntis on a clear day.

Phase 4: Ancient Woods & Descent via Älpli

To close the loop, the trail guides you down the eastern spine of the ridge through the Steckenband, keeping majestic views in front of you. As you descend toward Alp Älpli, you will witness a magical ecological transition. The harsh, barren rock gradually softens as you slip into a beautiful, ancient subalpine forest (Bödmerenwald).

This section of the hike is incredibly peaceful - moss-covered rocks, gnarled ancient trees, and old-growth pine provide cool, welcome shade after hours on the exposed limestone plateau. Keep your eyes & ears open - listen closely for the sharp, alarming whistles of alpine marmots - before the trail loops you gently back to the pass road.

Alternative Routes & Possible Extensions

One of the best things about the Silberen area is that you don’t have to stick strictly to the classic route. There are various alternative paths and extensions criss-crossing the plateau depending on how much gas you have left in the tank:

• Extended Outer Loop (+/- 860m Descent): Instead of turning right at the main Silberen summit cross to begin the standard descent, you can choose to press straight ahead along the higher plateau ridge. The trail extends outward, deeper into the alien landscape, before eventually looping back hard to the left to reconnect with the path back to the Pragelpass.

• This extended loop pushes the distance to roughly 13 Km and increases your total vertical challenge to around 860 m - perfect for hikers looking for a longer, even quieter day in the backcountry.

Trail Hazards & the "Dry Whiteout"

Silberen plays by its own rules. The terrain features highly specific, potentially life-threatening hazards that every hiker must prepare for:

• "Dry Whiteout" (Trap of Alpine Fog): Because this monochrome rock landscape looks identical in 360 degrees, if alpine fog (Nebel) unexpectedly rolls in, you will instantly lose all depth perception and horizon lines.

• Navigation Blackout (Hidden Markers): This route is navigated entirely by following red-and-white alpine trail markers painted directly onto the limestone (in fairness there are an awful lot of these). Patchy summer snow fields (which frequently linger well into July or August) can completely bury them. 

• You must stick to the marked trail as closely as possible. Do not take shortcuts. If you lose the path, retrace your steps to the last visible marker and consult your offline [Komoot] GPS map.

• Deceptive Karst Holes: Melting summer snow creates thin, hollow "snow bridges" over deep, vertical fissures (grikes & dolines). If you step on a weak spot, the snow can collapse beneath you, causing a dangerous fall onto jagged, razor-sharp rock edges.

• Polished Limestone: Because this trail is highly popular, decades of hikers have worn down the main path. Even on a perfectly bone-dry, sunny day, some of the slanted stone steps have become smooth and highly polished, making them surprisingly slick.

Gear for the Terrain

• Sturdy, High-Ankle Hiking Boots: Lightweight sneakers or trail runners will not cut it. You need stiff boots with deep tread to prevent ankle twists on the fractured stone and to bite into unexpected slick spots.

• Trekking Poles: Essential safety tools, not just walking aids. Always use your poles to aggressively probe the snow ahead of you before committing your body weight to check for hollow spaces underneath.

• Emergency Headlamp: Even if you plan to be back hours before dark, always pack a headlamp in your kit. If a sudden fog delay occurs, or navigating the broken rock slows you down, you do not want to be trapped trying to find painted trail markers on a fractured mountain plateau in the dark.

Reward Your Efforts: Food & Fellowship on the Pass

Once you successfully complete the loop and drop back down to the pass, don't rush to pack up the car. The Pragelpass offers a wonderfully cozy alpine wind-down that provides the ultimate reward for your physical efforts.

Local Food Options

The local culinary offerings on the pass are fantastic for refueling after burning all those calories on the rock plateau. You have two incredible ways to experience the local flavors:

• Berggasthaus Pragelpasshöhe: This traditional mountain inn is the ideal spot to pull up a chair, sit out on the terrace, and order hot, comforting Swiss alpine fare. Note: It runs strictly on cash, so make sure to bring enough Swiss Francs with you!

• Direct from the Alpine Dairies (Alpkäserei): During the summer pasture months, you can buy award-winning Pragel-Alpkäse directly from the local farmers down the road. This rich, aromatic cheese is made right on the surrounding meadows from cows grazing on fragrant alpine herbs.

Historical Pragelpass Chapel (Pragelkapelle)

Before you leave, take a short, peaceful stroll over to the charming little alpine church sitting proudly near the pass summit. Dedicated to St. Wendelin, the patron saint of alpine herders and livestock, this beautiful chapel was originally constructed back in 1715. 

It was built by local mountain farmers as a place of sanctuary and worship so they wouldn't have to make the long, arduous journey down to the valley churches during the summer farming season. 

The simple stone chapel features a cozy, beautifully preserved interior that stands in peaceful, warm contrast to the wild, brutalist rock architecture of the limestone moonscape you just conquered above.

Logistics: Getting to the Trailhead

It’s important to know before packing your bag that you absolutely need a car for this hike:

• No Public Transport Access: Swiss post buses run up to the entrance of the Hölloch Caves on the Schwyz side, and up to Klöntalersee/Richisau on the Glarus side. However, public transport completely stops there. The remaining stretches of the narrow road leading up to the Pragelpass summit have no public transit connections - see my other articles on hiking these sections.

• Weekend Driving Rule: If you are planning a weekend trip, keep driving regulations in mind. The Glarus side of the Pragelpass road enforces a strict motorized vehicle ban on Saturdays & Sundays. To park at the trailhead on a weekend, you must drive up to the pass exclusively via the Muotathal (Schwyz) side.

This route was hiked to the left in 2021 and to the right in 2025 by the Author. See my other articles on hikes and climbs in the area. Contact me by email for photos or to ask questions...