Glacière de Monlési

Glacière de Monlési is a natural ice cave in the municipality of Val-de-Travers, canton of Neuchâtel, in the Swiss Jura. Cold winter air sinks into a karst shaft and stays trapped there through summer, so ice remains underground all year. It is regarded as the largest underground ice deposit of the Jura arc.

What is the Glacière de Monlési?

It is a karst sinkhole with three shafts leading down to a large chamber filled with ice. The entrance sits on a high plateau at roughly 1,127 m above sea level, and the main shaft is about 20 m deep. Ice volume is estimated at 6,000 m³, although some sources quote up to around 10,000 m³. The air inside hovers near 0 °C. The site lies above the village of Couvet and is protected as a nature reserve.

How do you get there?

Most hikes start in Saint-Sulpice or at the Les Sagnettes bus stop (Col des Sagnettes) on the road between Fleurier and La Brévine. The cave is often combined with the Corridor aux Loups in one loop, and some routes also pass Lac des Taillères. The turn-off is not marked on any trail sign, so carry a map or a GPS track.

What is the descent like?

The largest opening hides between trees and bushes. A steep path with a safety cable leads to the entrance, followed by a metal ladder. Hiking sites grade the descent T3: you need sure feet, a head for heights and good footwear.

What should you bring, and when should you go?

• a headlamp, because there is no lighting inside,
• a warm jacket and gloves,
• shoes with good grip, since ice and ladder rungs can be slippery.

The recommended season runs from April to October, when the approach is dry and the ice is still visible.

Frequently asked questions

Can you visit Glacière de Monlési all year?

Ice is there year-round, but visits are recommended from April to October. In winter the path and ladder ice over and the approach gets much harder.

Do you need caving gear?

No, this is not a technical caving trip. A headlamp, warm clothing and sturdy boots are enough, but you must be fit and comfortable with heights.

Where do you start?

Les Sagnettes bus stop and Saint-Sulpice are good starting points. Check the Neuchâtel regional transport timetable for current connections.

How long does the trip take?

Loops via the Corridor aux Loups or Lac des Taillères take a few hours, while the walk from Les Sagnettes straight to the cave is shorter. Timing depends on the route you pick.