Switzerland, the country of four seas

Lake Toma, located at 2,343 metres above sea level, known as Lai da Tuma in Romansh, on the Oberalp Pass in canton Graubünden, is officially considered the source of the Rhine, which eventually flows into the North Sea. Alessandro Della Bella / Keystone

Switzerland is a landlocked country with no direct access to the sea. Yet it is connected to four seas. What sounds paradoxical is a geographical peculiarity in Europe: rain and meltwater from the Swiss Alps flow into four different seas.

A drop of rain that falls in the Swiss Alps can at some point later flow into the sea with millions of others in very different places: into the North Sea, the Mediterranean, the Black Sea or the Adriatic.

This is made possible by Switzerland’s special location in the heart of Europe. The Alps form one of the continent’s most important watersheds.

It is from their passes and peaks that the path of the water is decided – often over thousands of kilometres into one of these four seas.

The ‘water castle of Europe’

Since the 19th century, Switzerland has been known as the “water castle of Europe”. Although it stores only a small proportion of Europe’s fresh water, many large rivers originate in Switzerland or receive a significant amount of water from the country. The four most important are the Rhine, the Rhône, the Ticino and the Inn.

Kai Reusser / SWI swissinfo.ch

According to the Swiss Academy of Sciences (SCNAT)External link, around 65% of the country’s surface drains via the Aare, Reuss and Rhine through Germany, northern France and the Netherlands towards the North Sea.

Around a quarter of the runoff from Switzerland follows the route through southern France to the western Mediterranean via the Rhône and Lake Geneva.

The southern part of the Swiss water reaches the Adriatic Sea via the Ticino and the Po through Italy, while the Inn flows from the Engadine via the Danube into the Black Sea, through Austria, Slovakia, Hungary, Croatia, Serbia, Romania, Bulgaria, Moldova and Ukraine.

In the Ukrainian oblast (district) of Odessa, the Danube, and with it water from the Inn, flows into the Black Sea. Keystone / Laif / Jörg Modrow

The Gotthard massif, from which most of these rivers originate, plays a central role. From a hydrographic perspective, Switzerland is therefore considered a European hub in terms of various water parameters.

A special geographical feature is located at the Lunghin Pass in canton GraubündenExternal link, where the catchment areas of the North Sea, Adriatic and Black Sea meet.

Such so-called triple watersheds or triple points, where water can flow in three directions, are rare worldwide.

In North America, the Triple Divide Peak in Montana is well known, and in Australia there are similar points inland. However, unlike there, in Switzerland these are not remote places, but a densely populated, economically strongly networked area in the heart of Europe.

Water reserves of continental importance

With an average annual rainfall of around 1,500 millimetres and numerous natural reservoirs – the largest of which are Lake Geneva and Lake Constance – Switzerland has above-average water resources.

Because clouds accumulate in the Alps, it rains more here than in many other countries. According to MeteoSwissExternal link, the annual amount of precipitation that falls over the whole of Switzerland is roughly equivalent to the capacity of Lake Constance.

In addition to the drinking water supply and agriculture, these water resources play an important role in energy production in Switzerland.

Depending on the annual amount of rainfall, between 55% and 60% of domestic electricity is produced from hydropower.

This makes Switzerland one of the leading hydropower countries in Europe. The storage and pumped-storage power plants in the Alpine region with their reservoirs not only supply electricity for Switzerland’s own needs, but also contribute to grid stability in neighbouring countries.

The Rhône Glacier at the Furka Pass in the Valais Alps, which has suffered massive glacier retreat in recent decades and whose waters flow into the Mediterranean, is being partially protected from rapid melting with special white blankets. Urs Flüeler / Keystone

Glacier shrinkage and contaminated groundwater

However, Switzerland’s “water castle” is also built on ice: Switzerland’s water resources have been dwindling for decades due to the increasing retreat of large glaciers in the Alps.

As a result, source areas are shifting, water runoff is becoming more irregular and new storage and protection strategies are becoming necessary because melting glaciers can also significantly increase natural hazards.

For example, on May 28, 2025, the Birch Glacier above the Valais village of Blatten broke off and buried almost the entire village. Blatten is to be rebuilt with a strict, risk-based safety concept.

Due to climate change, Switzerland has also been struggling with more drought recently. A new national monitoring and warning system is to secure the water supply for the future.

Glacier retreat and increasing drought are also causing a shortage of groundwater, which in the Central Plateau is often contaminated by pesticide residues and nitrate pollution.

However, experts say the groundwater in Switzerland can continue to supply the population with a very stable supply for many decades to come.

On November 1, 1986, shortly after midnight, a major fire broke out in a production hall belonging to the Basel-based chemical company Sandoz in Schweizerhalle, in canton Basel Country. The warehouse destroyed by the fire contained over 1,000 tonnes of insecticides and pesticides. Hundreds of thousands of fish died in the Rhine as a result of the toxic firefighting water that entered the river. Keystone / Gardin

Responsibility downstream

As a water reservoir, Switzerland also has a great responsibility towards the countries in the lower reaches of its numerous rivers. As already mentioned, the waters connect Switzerland with over a dozen neighbouring and riparian countries.

Both the quantity and the quality of the water that flows out of Switzerland have an impact on millions of people and river animals outside the country’s borders.

This was demonstrated by the chemical accident at Schweizerhalle in 1986External link, when a warehouse containing chemicals at the Sandoz company burned down and the Rhine was poisoned. The pictures of the dead fish went around the world.

Or the dispute over the discharge volume of Lake Maggiore, the level of which is regulated at the end of the lake in Italy. Heavy rainfall can cause this lake to rise sharply within a short space of time.

The Borromean Islands, located in the Italian part of Lake Maggiore. Keystone

This results in cross-border obligations: in flood protection, in the preservation of ecosystems and in water management in times of increasing drought.

This is why Switzerland is actively involved in international organisations such as the International Commission for the Protection of the RhineExternal link and the World Water CouncilExternal link to promote common standards and early warning systems. Although Switzerland does not touch any seas or oceans, it is closer to them than you might think.

Edited by Balz Rigendinger. Translated from German by AI/ts

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