Aigüestortes i Estany de Sant Maurici National Park

Listen first. Water is moving somewhere close by. It is not one sound but many: a thin trickle over granite, a deeper rush beneath a footbridge, a soft lapping at the edge of a lake. The air smells of pine resin and cold stone. Underfoot, the path is a mix of packed earth, roots and pale rock polished smooth by countless boots. Welcome to the high Pyrenees of Catalonia, and to a park whose very name is about water.

Aigüestortes means, roughly, twisted waters. The name comes from the way mountain streams here wander across flat meadows in loops and curves, splitting and rejoining before they find their way downhill. The second half of the name points to one lake in particular, the Estany de Sant Maurici. Estany is the Catalan word for lake, and you will hear it often here. Put together, the name holds the two faces of this place: winding streams in the west, and a deep mountain lake in the east.

This is the only national park in Catalonia, and it is one of the oldest in Spain. It was declared in 1955, at a time when protected landscapes were still a new idea in the country. The park sits in the province of Lleida, in the far north-west of Catalonia, close to the French border. It spreads across several historic districts, including the Pallars and the Alta Ribagorça. Villages such as Espot on the eastern side and Boí on the western side act as its main gateways.

Now look at the shape of the land around you. Almost everything you see was carved by ice. During the last ice ages, glaciers filled these valleys and ground them into wide, U-shaped troughs. When the ice melted, it left behind hollows in the rock, and those hollows filled with water. The result is one of the densest groups of mountain lakes in the whole Pyrenees. Depending on how you count them, the park and its surroundings hold around two hundred lakes, from wide sheets of water to small dark pools.

The rock itself tells you a lot. Much of the park is granite, pale grey and speckled, often rounded into smooth shoulders. In other areas you will find darker slate and other older rocks, which break into sharper, flakier edges. Look at the boulders scattered across the meadows. Many of them were carried here by glaciers and dropped when the ice retreated. Geologists call them erratics. To a walker, they are simply good places to sit, eat lunch and watch the light change on the water.

If you are near Lake Sant Maurici, raise your eyes to the twin peaks that rise above its southern shore. These are Els Encantats, which means the Enchanted Ones. Their two rocky towers have become the symbol of the park. Locals tell a well-known legend about them. According to the tale, two hunters skipped Mass on the feast day of Saint Maurice to chase chamois in the mountains. As punishment, they were turned to stone, and they still stand here today. It is folklore, of course, but once you hear it, the peaks are hard to see any other way.

Now for something many visitors miss. Some of these lakes are not entirely natural in their present form. During the twentieth century, engineers built dams on a number of them to produce hydroelectric power. Lake Sant Maurici itself is held back by a dam. Look closely along certain shorelines and you may see a pale band of bare rock above the waterline. That band shows how the water level rises and falls with the needs of the power system. Wild as it feels, this landscape has also worked for the valleys below.

The forests change as you climb. Lower down, you may walk through silver fir and birch, with damp moss on the ground. Higher up, the mountain pine takes over. It is a tough, dark tree that can grow at heights where few others survive, often twisted by wind and snow. Above the last trees, there are open alpine meadows. In early summer they fill with wildflowers, and the grass is cropped short by grazing animals. In autumn, the birches turn yellow and the slopes take on a warm, rusty colour.

Keep your eyes open for animals. The chamois, a nimble mountain goat-antelope, is often seen on rocky slopes, especially in the early morning. In Catalan it is called the isard. You may also hear a sharp, high whistle from the rocks. That is the marmot, a stocky ground-dwelling rodent that warns its neighbours of danger. Look up as well. Golden eagles hunt over these valleys, and with luck you may see a bearded vulture, a huge bird with long, narrow wings and a wedge-shaped tail.

You may notice that cars do not drive deep into the park. Private vehicles are restricted on the inner tracks, which helps to keep the valleys quiet. Many visitors reach the lakes on foot from Espot or Boí. Others use the four-wheel-drive taxis that run from these villages along the mountain tracks. Once you leave the track, the only sounds are water, wind and the occasional cowbell from a herd grazing below. That quiet is part of what the park protects.

For serious walkers, the park is famous for a long circular route that links its mountain refuges. It is known as Carros de Foc, which means chariots of fire. Hikers walk from one refuge to the next over several days, crossing high passes and sleeping in stone huts. You do not need to attempt anything so ambitious, though. Even a short loop around one lake gives you the essential experience: granite, clear water, pine and an enormous sky above the ridges.

If you have time after your walk, the valley of Boí on the western edge of the park holds another kind of treasure. Its small villages contain a remarkable group of Romanesque churches. Romanesque is the style of medieval Europe before the Gothic, with thick walls, round arches and tall, square bell towers. These churches are listed by UNESCO as a World Heritage Site. Seeing them after a day in the mountains feels fitting. Both the stone towers and the stone peaks have watched over these valleys for a very long time.

Before you move on, stop for a moment wherever you are standing. Look at the colour of the water nearest to you. It may be green, steel grey, or almost black, depending on the depth and the sky. Notice how the reflection of the peaks breaks apart each time the wind crosses the surface. Listen again for the streams, still twisting their way down through the meadows. As you walk away, that sound will follow you for a long while... and then, quietly, it will be gone.