The mysterious Lago Cadagno Exploring the extraordinary Val Piora with microbiologist Raffaele Peduzzi.



Everything is a little different in the Val Piora. Situated at 2,000 metres above sea level, this high mountain valley in the canton of Ticino boasts an extraordinary diversity of fauna and flora, along with more than 20 mountain lakes – one of which is so mysterious that it attracts researchers from all over the world. Microbiologist Raffaele Peduzzi explains what it is that makes the Val Piora so special – for day trippers, hikers and researchers alike.

Val Piora, Ticino

The Val Piora valley lies in the very north of Ticino, above the village of Quinto. The high mountain valley is known for its many bodies of water.

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The three largest lakes: The famous Lago Ritóm on the left, the mysterious Lago Cadagno in the foreground on the right and the small Lago di Tom lying above them in the centre.

A lake with many mysteries in its depths


Suspiciously large numbers of fish

The density of the fish population in Lago Cadagno much greater than in other mountain lakes. People have known about this remarkable wealth of fish for centuries. Researcher Felix-Ernest Bourcart first took samples from the lake bed back in 1903. In doing so, he noticed that the water from this part of the lake was very dark in colour and carried a smell of sulphur, in stark contrast to the water at the lake’s surface.

It would be very interesting to carry out detailed research into this curious lake.
Felix-Ernest Bourcart, the first researcher at Lago Cadagno, around 1906

Completely in his element

Microbiologist Raffaele Peduzzi from Airolo has been researching the high mountain valley for around 40 years. The main focus of his research is Lago Cadagno, a unique phenomenon within the Alps. In 1994, the Alpine Biology Centre was founded here to facilitate on-site research into the lake and high mountain valley. 

Raffaele Peduzzi is an honorary citizen of Quinto and used to visit the Val Piora as a child.

A lake with pink water

Much has happened over the last 100 years. Raffaele Peduzzi, along with scientists from Switzerland and abroad, has carried out thorough investigations of the mountain lake and made some startling discoveries. For instance, the fact that Lago Cadagno is made up of three different layers of water that do not mix. 

Microorganisms rule supreme here 

The lower layer is fed by springs on the lake bed and enriched with salts from the Dolomite rocks. This makes it heavier and unoxygenated. The upper layer of water contains granite minerals and is very rich in oxygen – ideal conditions for the fish found here. However, it is the middle layer that is the most exciting. This layer is home to a very special sulphur bacterium living at a depth of 11–13 metres. And it is pink!

Lago Cadagno is a rare phenomenon known as a meromixis.
Raffaele Peduzzi, microbiologist

The chemistry is right for day trippers too

But don’t worry: Even those with no interest in microbiology will enjoy a visit to Val Piora. With more than 20 mountain lakes nestled idyllically in the mountain scenery, the high mountain valley is a paradise for hikers. As well as the mysterious Lago Cadagno, Lago Ritóm is well worth a visit. This artificial lake was created more than a hundred years ago to supply energy for the construction of the Gotthard line. A nature trail running along the right-hand side of the lake invites visitors to see the region in a new light. For those with sufficient reserves of energy, a detour to the small Lago di Tom comes highly recommended. 

  • 500 cows In summer, 300 cows and 200 oxen graze on the Alpe Piora. 
  • 3–4 hours The duration of the circular hike from the upper station, along the shore of Lago Ritóm to Lago Cadagno (and the hut of the same name), and back again. 
  • 88% gradient The Ritóm funicular railway is one of the steepest mountain railways in the world.
The sheltered location, the climate and the geology all help sustain the remarkable diversity of flora and fauna up here.
Raffaele Peduzzi, microbiologist
Feeling peckish? The Capanna Cadagno serves up local specialities.

Exploring makes you hungry 

If you are in need of some sustenance after an educational excursion or a mountain tour, head to the cosy Capanna Cadagno.  With relaxing views over Lago Cadagno and contented grazing cows, the hut serves up outstanding Ticino specialities such as homemade gnocchi and Ticino platters with Piora cheese and prosciutto from the alp. Prosciutto crudo Piora is a type of cured ham that is stored for two whole summers on the Alpe Piora, where the fresh mountain air and the many herbs give it its delicious flavour.