Inside France's Mer de Glace Ice Cave

Inside France’s Mer de Glace Glacier

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Have you ever seen a glacier up close?  Hiked along one, touched it, or possibly hazarded a crossing?  If so, you’ll know they’re powerful forces of nature, hulking masses of snow and ice, creeping downhill so imperceptibly they could easily be mistaken for sleeping giants.

When we lived in the States, we’d mostly only seen glaciers from afar in national parks in the American Northwest and Canada. Most of them were but distant specks of dirty white, slivers of light in the crevices of mountain fissures.  Until recently, our most intimate experience with glaciers had been a killer hike along Switzerland’s Aletsch Glacier, the largest in the Alps.  Despite getting up close and personal with it, we weren’t able to go inside it. In fact, we didn’t realize it was something a person could readily do until we returned to Chamonix to do some hiking in the French Alps.

Wonder what it’s like hiking inside a glacier? A loop trail through Mer de Glace takes you up close and personal with a glacier in the French Alps.

Map of Mer de Glace glacier in France
A map near Chamonix, France shows a handful of glaciers in the immediate area.

With plans to meet up with two of our oldest college friends who were flying in from the States, we hit the road for Chamonix early in the morning before their plane even touched down in Geneva.  We didn’t have reservations for the night, so our plan was to scout out a place for us all to camp before they arrived.

As soon as we entered the narrow, bumpy, tree-lined road to Camping de la Mer de Glace in the famous alpine town of Chamonix, we knew we’d found our home for the next couple of days.  Gloomy fall weather had heralded an end to the region’s touristy summer season, and it was too early for the deluge of winter sport enthusiasts to descend upon town.  Except for the campground’s exceptionally friendly owner, we had the peaceful, wooded grounds virtually to ourselves.

The spiky needles of the French Alps surrounding the Mer de Glace Campground are obscured by clouds.

Trav and I set up camp, then impatiently waited for our friends, Archie & Angie, to arrive.  With no way to contact them, we realized we might be in for a wait.

Anxious to explore, we asked the camp host  for her recommendations on nearby hikes.  When we told her we were up for a challenge despite the threatening clouds and intermittent patter of icy rain, she didn’t hesitate in recommending Mer de Glace Glacier.  Joining her outside the campground office, our gaze followed the sweeping motion of her arm as she pointed roughly east – up, up, and up toward a narrow gap in the mountains.   Though the glacier was invisible, masked by the mists swirling among the peaks, she assured us that folks traveled to Chamonix from all over the world just to visit it.

Throwing together a single pack, we strapped on Touille’s warmest fleece jacket and hit the trail.

Engineers have bored tunnels beneath the glacier to access its seasonal melt water, funneling it down into the valley to a power plant for hydroelectricity.  Below the dam, water is released back into the river.

With our camp host’s directions in mind, we briefly followed the trail along L’Arveyron, a small river hastily delivering melt water from the glacier to the valley below.

Crossing the river, we spotted an old homestead with a charming barn.  Sporting a curious mixture of license plates, antlers, and tattered old hiking gear, I loved it immediately.

An old barn near the Arveyron River still bears the tattered boots and backpack of a fellow hiker on the trail to Mer de Glace.

Smiling at the homestead’s ancient Basset Hound who didn’t even lift his head as we passed, we reached a fork, turning right.  For the next two hours, we climbed steadily uphill.

Chamonix, France
Travis looks down on the town of Chamonix while I catch my breath.
Train to Mer de Glace glacier above Chamonix, France
For those not interested in hiking, a train is also available to whisk tourists from Chamonix to the glacier.

Shortly before 5 pm, we finally saw a building above us and knew we must be nearing the end of our ascent.

We pass the Glaciorium, an exhibition about glaciology, before arriving at the Montenvers Rail Station.

Passing the deserted Glaciorium, we continued on to the 19th century Grand Hôtel du Montenvers, an imposing building that loomed through the shifty clouds like an isolated sanitarium, forlorn and forgotten. 

The Hotel du Montenvers stands above Mer de Glace Glacier just beneath the French Alps.

Had it not been for an old black and white photo from 1921 that I’d seen on the wall of our campground’s dining hall, I wouldn’t have suspected what towered just above us.  All we could see were thick clouds occasionally parting to reveal impossibly tall ribbons of nearly vertical waterfalls across the valley.  The jagged aiguilles – or needles – as so many of the peaks are named, were completely obscured.

A photo of the Hotel du Montenvers from 1921 reveals the building beneath the towering Aiguilles du Dru.

Chilled, wet, and with my hopes set on a hot cup of coffee once we reached the top, I was disappointed to find everything closed at the Montenvers Train Station except for the ticket office.  The last train back to Chamonix would be departing in just a few minutes.

Visitors who hike up to Montenvers to see the glacier can buy a one-way ticket to ride the train back to Chamonix.

This left us with a bit of a dilemma.

We were anxious to get back to the campground to meet up with our friends, but we were appalled that two one-way tickets cost €50.  Plus, taking the last train down wouldn’t leave us time to see the glacier up close.  The cable cars down to the glacier were closed for the evening, so our only option would be to hike down and up again before our return hike to Chamonix.  We could either see the glacier, which would mean a lot more hiking, or we could relax as the train zipped us down to a hot shower and a warm drink.

The cable car near the Montenvers Train Station transports visitors down to the glacier during regular business hours.

We hadn’t even seen the glacier yet, not even from our vantage high above it.  It was still somewhere a bit further up the trail.  At least wanting to catch a glimpse of it, we continued along the trail a bit further past the train station until the telltale signs of the glacier came into view.

Mer de Glace glacier in the French Alps
The Mer de Glace glacier curves along the northern slopes of the Mont Blanc massif in the French Alps.

Peering down through the trees, we could see small spots of bright blue in the dirty ice sheet.

Ice caves!

The ice cave is visible as a bright blue spot in the gray ice of the glacier below Montenvers.

Shrugging off all thoughts of cold, the late hour, the rain, and the 2-3 hour hike back to Chamonix in the growing dark, we set off down the trail to investigate the ice cave.

The steep rocks in the trail quickly gave way to a long series of grated metal stairs anchored into the sloped face above the glacier.  We took turns carrying our dog, Touille, for much of the hike since the gaps in the metal grating were bigger than her tiny little  feet.  It didn’t take us long to reach the bottom of all 420 steps and to cross a long grated walkway above a fissure in the glacier.

Much of the trail down to the ice cave consists of grated metal stairs.

Reaching the cave’s entrance as it started to pour, we ducked inside and were promptly swallowed by the darkness.

The mouth of the Mer de Glace Ice Cave glows with an unearthly pale turquoise light.
We follow the short loop trail through the glacial cave.

With just our cell phone flashlights, we made our way carefully around the circular man-made tunnel, stopping to pick out a variety of exhibits.  Grottus, or ice carvers, had made several large fireplaces (ironic, of all the things they could have carved), old photos lined the walls, and electric wiring was taped in bundles along the floor.  During normal business hours, the entire cave is illuminated with bright neon lights.

Grateful we were able to experience it in a more natural state, I stared in awe for quite some time into the thick ice sheet.  Incredibly black but transparent, millions of bubbles hung suspended in the ice.  It was absolutely beautiful.

The ice near the cave’s entrance is an exquisite shade of turquoise.

Stopping to read several informative signs, I was amazed to find out the glacier was moving all around us at an average of a centimeter an hour where we stood.   That’s fast enough to notice movement in a single afternoon!  Since the glacier moves so quickly, the cave never remains in one place.  Each year the force of the glacier pushes the cave down the valley, and each year, the grottus return in the spring to hack out a new cave for visitors to enjoy.

Ready to return to our campsite, we left the relative dryness of the peaceful cave, re-tracing our route up the slippery steps.  As always, the going up was worth the coming down, but I quickly fell behind as Travis went ahead to scout for a different return route.

The quiet valley was suddenly split by a resounding crack that echoed off the valley walls. I froze, scanning the valley for movement.

As soon as I met up with Travis at a Y in the trail, I excitedly gushed,

Did you hear that?!

He nodded, his eyes also lit with interest.

While I insisted the sound had come from within the glacial ice, he thought it was perhaps a rock slide.  Either way, it was eerie and completely awesome.

Water cascades down the walls of the glacial valley above Mer de Glace.

Rather than returning via trail 26, we took an alternate route – trail 25 – that was shorter.  It was also steeper.  I was grateful for my warm Danner hiking boots as we slogged along the flooded trail above the glacier.  Quickly losing elevation, we picked our way downhill over boulders slick with rain.

Particularly difficult sections of the trail have fixed ladders or small metal foot pegs embedded in the steep boulders.

Descending into a murky fog bank, we passed the Buvette des Mottets, a small mountain chalet with outdoor seating and deer-shaped flower pots.

Struggling to make out the trail, I followed a smooth patch of rock below the chalet to a slight hump, pausing on top to peer into the gloom.  Tentatively feeling my way forward with one boot, only open air met my foot.  I definitely was no longer on the trail!

Back tracking slightly, we continued without incident to a short section of gravel road, eventually meeting back up with the same trail we’d taken on the way up.

The trail becomes increasingly difficult to discern in the fog and fading light.

We arrived back at the campground to find that Archie and Angie had arrived!

Exchanging warm hugs amidst excited chatter, we then bee-lined for the on-site pizza stand before it closed for the evening.  Setting up shop in the warm campground dining hall, we could finally relax, lingering over dinner.

Camping Mer de Glace has a warm and cozy rustic dining area for guests.

Since we’d last seen our friends well over a year before, we’d moved to Europe and they’d welcomed their first baby – two huge life changes.  We had a lot of catching up to do.

We’re excited to see Arch and Ang in Chamonix. Two of our oldest friends, they’re typically our “go-to” adventurers when we need a weekend getaway to a national park or a last-minute camping trip.

After dinner, I thankfully grabbed a hot shower before the reunion reconvened at our tents.  We laughed and drank wine, swapped stories and merrily sent laughter drifting up into the night sky well into the wee hours.  Finally falling into our sleeping bags, we grabbed a few hours of rest to recharge for another day of adventure in the French Alps.

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Know Before You Go
  • Camping de la Mer de Glace is the nearest campground to the glacier.  The trail to the glacier goes right past the campground.
  • The Glaciorium is an exhibition on glaciology and is typically open from June to September.
  • Guests who prefer luxury accommodations can book a room at the Grand Hôtel du Montenvers overlooking the glacier.  Rooms start at €250 per night.
  • The ice cave is “alive” and is constantly moving downhill.  It’s open seasonally, so check their schedule before you book your travel.
  • Round-trip train tickets from Chamonix to Montenvers (just above the glacier) cost €32.50 per adult.  This includes a gondola ride down to the glacier and entrance to the ice cave.  One-way tickets from Chamonix to Montenvers or Montenvers to Chamonix (plus gondola and ice cave entrance) cost €26.50 per adult.
Map of Mer de Glace Hike

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