Bosque de Fray Jorge National Park

Listen for the drip. Under the trees here, water falls in slow, scattered drops from the leaves above, even on a day without rain. The air is cool and damp against your skin. It smells of moss and wet bark. Then you walk a few steps toward the edge of the ridge and look inland... and the land below is dry, dusty and covered in cactus. That contrast is the whole story of this place.

You are standing in Bosque de Fray Jorge National Park, in the Limarí Province of Chile's Coquimbo Region. This is the southern edge of one of the driest parts of the world. The great Atacama Desert lies to the north. Rain is rare and unreliable here. And yet, on the tops of these coastal hills, there is a green, shaded forest of the kind you would normally expect to find many hundreds of kilometres to the south, in the rainy lake country of southern Chile.

So where does the water come from? The answer is the sea. Most mornings, a thick bank of fog rolls in from the Pacific Ocean. Chileans call this coastal fog the camanchaca, a word that comes from the Andean world. The fog rises against the hills of the coastal range, which locals call the Altos de Talinay. Here the moist air meets the trees, and the trees catch it.

This is the first surprise of the forest. The leaves do not wait for rain — they collect water directly from the air. Tiny droplets of fog settle on the leaves and branches, join together, and run down to the ground. Scientists call this fog interception. In effect, the forest waters itself. Without the daily fog, these trees could not survive on this coast, and the dry scrub below would take over the hilltops.

The second surprise is the age of this forest. Botanists consider it a relict, which means a survivor from an earlier time. Thousands of years ago, the climate of north-central Chile was wetter, and forests like this one were much more widespread. As the region became drier, the forests retreated south. Only a few islands of trees stayed behind, on hilltops where the fog still arrives. Fray Jorge is the most famous of these islands.

Look closely at the trees around you. One of the most important species here is the olivillo, a tall evergreen with leathery leaves. You will also find the canelo, a tree with pale bark and fragrant leaves. In Mapuche culture, the Indigenous culture of southern Chile, the canelo is a sacred tree. It is unusual to meet it this far north, so far from its usual home in the wet south.

Now bring your eyes down to the smaller life. Ferns grow along the shaded ground. Mosses cover fallen logs and the lower parts of trunks. Pale grey and green lichens hang from the branches. Some plants grow directly on the trees themselves, using them as support. Plants like these are called epiphytes. All of them depend on the steady moisture of the fog. In this forest, even the smallest green surface is a sign that water is present.

The forest itself covers only a small part of the park. Most of the protected land is semi-arid scrub, the vegetation of dry hills. As you drove up the access road, you probably passed through it. There are low thorny bushes, columnar cacti and hardy shrubs that turn green after rare winter rains. This dry landscape is important too. It shows exactly what the hilltops would look like if the fog stopped coming.

The name of the park, Fray Jorge, means Friar George. Fray is the Spanish title for a friar, a member of a Catholic religious order. The origin of the name is not well documented. According to a popular local account, the forest was named after a friar from the colonial period who visited or lived in this area. Treat that story as tradition rather than firm history — the details are uncertain.

What is well documented is the effort to protect the forest. Chile declared this area a national park in the first half of the twentieth century. Later, in 1977, UNESCO recognised Fray Jorge as a Biosphere Reserve. That is an international status for places where nature and scientific study are protected together. For decades, ecologists have used the park to study how dry ecosystems respond to changes in rainfall and climate.

Keep an eye on the ground and the open slopes for animals. Foxes live in the park, and they are often seen near the roads and the visitor areas. Small rodents called degus, which are native to central Chile, run between the shrubs. Many birds move between the dry scrub and the forest edge. Please do not feed any of the animals. Human food harms them and changes their natural behaviour.

The forest walk follows a short trail along the ridge, partly on wooden walkways. The walkways are there for a reason. The soil here is fragile, and the roots of the trees sit close to the surface. Stay on the path, and the forest will last for future visitors. Walk slowly. The best moments here are quiet ones: the drip of water, the movement of the fog through the branches, the sudden view of the ocean through a gap in the trees.

Before you leave, stop for a moment at the edge of the trees. On one side, there is shade, moss and the steady sound of falling drops. On the other side, there is sun, dust and cactus. The line between them is very narrow. Breathe in the cool air one more time. As you walk back toward the dry hills, notice how quickly the green disappears... and remember that every leaf behind you lives on the fog from the sea.