On one level – the deepest – Gosainkund is similar to other lakes in the mountains which are pilgrimage destinations and sites of shamanic ritual. Tamangs come here in a similar way as Rais go to Salpa, with the difference that their religion includes elements of Tibetan Buddhism that the Rai tradition doesn’t. For them the Buddhist master Guru Rinpoche is present here, in addition to a shamanic pantheon.

There’s also a deep Hindu layer at Gosainkund. This tradition relates to a famous event when the gods churned an ocean of milk, which produced a poison that the great god Shiva drank to save the world. The poison turned his throat blue and, in central Nepal at least, it’s believed that Gosainkund is the place where he struck a mountain with his trident and released water to quench his burning thirst. A Hindu pilgrimage to Gosainkund is first recorded in 1447, when a king from the Kathmandu Valley made an elaborate journey here. This was a period when Kathmandu flourished as a prosperous cultural centre, based on trade with Tibet. It’s significant that Gosainkund lies on the ridge above an important trade route. In fact, its modern name refers to a religious order, the Gosains, who were both holy men and merchants.

There’s a wonderful 19th-century painting, probably copied from an earlier original, which records the journey of a group of seven pilgrims, both women and men, from the Kathmandu Valley to Gosainkund. It seems that the pilgrims may have commissioned the work when they got safely home. The scene, which is over four metres long, is partly a landscape panorama, with white mountains along the horizon. It’s partly a narrative of their journey, even showing two of the women catching a third when she tripped. And it’s also partly a map, with seventy-seven places marked and labelled. On the left (to the south) are the cities of the valley, with palaces and temples quite accurately drawn inside their walls. In the cities the houses are tiled, but in the countryside there are circular thatched huts. Serpentine rivers and paths coil across the canvas, passing by distinct species of flowers and trees. Among the other lordly pilgrims, porters and merchants crowding the route, the seven subjects climb the steep paths like ladders, and then descend them like flights of stairs in the narrative method of a cartoon strip. There are naked Hindu babas sitting on tiger skins, and a Tibetan yogin in a cave guarded by a fierce dog. At Gosainkund there are throngs of devotees. The likeness of the recumbent god Shiva is visible beneath the water, and three springs gush into the lake where the prongs of his trident struck the rock.

This painting shows how Gosainkund was integrated, as a Hindu pilgrimage site, within the sacred landscape that the courtly Kathmandu Valley discovered around itself in its heyday. Gosainkund is made into an outpost of that nearby urban culture, which I wrote about in another book. Water from here is said to flow by a long tunnel to a spring inside the valley, at a temple called Kumbheshwar. Hindus and Tamang shamans celebrate there on the same full moon that the festival happens up here, as a more convenient alternative for those who can’t manage the journey. This idea – of water travelling long distances through an underground channel from a holy place in the landscape to another holy site, a temple – occurs at several places in Hindu South Asia, as a means for one place to share the other’s power.

In Kathmandu, I occasionally used to go to talk to a former foreign minister, a man who had a photograph in his sitting room of himself addressing the UN in New York. He told me once that this hydraulic tunnel from Gosainkund to Kumbheshwar (presumably a bit like the drinking water project from Melamchi) showed how advanced ancient Nepali engineering was. That was a very anachronistic point of view because obviously the idea used to be that the connection between Gosainkund and the city is innate, not a human contrivance.

On the August full moon of 1973, a geographer named Harka Gurung came here with a friend. He joined the pilgrims bathing in the water, which was as cold as it looked. He was basking in the sun afterwards, watching boys scoop coins from the shallows, when a novel idea flashed through his mind.10 If a keen numismatist, he wrote, could devise a better tool, or somehow dredge the lake, an archaeology of ancient coins might be recovered from Gosainkund. Kings came here to bathe after their coronations, so centuries of monetary offerings must lie on the bottom. When the sky is clear a massive pale slab can be seen in the blue depths (probably a piece of mica-gneiss, Dr Gurung supposed). It is identified as a self-made image of Shiva by Hindus and as the bodhisattva Avalokiteswara by Buddhists.

We didn’t pause at Gosainkund any longer than it took to realize there was nothing there for us, and walked on to Lauribina, which thank God isn’t far. When we gratefully entered the warm lodge we found a group of foreign tourists in one corner, and on the other side of the room a young baba, or sadhu, a Hindu mendicant, a kind of wandering monk. He was regaling a pair of eager environmental science students from Kathmandu while packing his chillum.

A sadhu is someone who has renounced everything and devoted his, or occasionally her, life to a perpetual pilgrimage, or sometimes to an intense and solitary religious practice in a single place such as a forest, or a cave on a wild mountain. The primal and ultimate sadhu is Shiva himself, who with total unconcern for his social image, naked except for animal skins, with wild hair and a cobra around his neck, set himself up on top of Mt Kailash to practice extreme austerities. His wife Parvati is the daughter of the mountains. Her father, Himavat, is the landscape itself, so the Himalayas have a great attraction for sadhus.

It’s said that many of them choose this life to escape an unhappy home, and their reputation is often as rogues and charlatans. They’re a wandering community of nutty, antisocial people. My wife once got a cheer, as a teenager, when she scolded a pair for smoking weed and had them thrown off a city bus. But occasionally a true saint will be found among them.

When Girish and I were in dry clothes we sat down with the sadhu, who told us about his journeys in a dull, stoned voice. At the time of the earthquake, when he happened to be in central Nepal, he saw a whole hill collapse. “It just fell into a river,” he said.

“I keep on moving and the move decides where I go. If I’ve been that way before, I know the road. If I want to travel a new road, if the weather’s favourable, then I go that way.” For sadhus, like all Hindus, and all pilgrims of any religion, places are objects of worship. But a sadhu’s whole life is an offering to geography.

Girish asked, “How do you manage your expenses?” “Some people give me things, like here,” he said. “They gave me marijuana.” His clothes were thin, his sandal was broken, and he’d been up at the lakes for three days. It was cold, he acknowledged, but it only becomes colder if you think about it. “This is good for me to sleep,” he said, indicating his chillum. “From here I’ll go down to Trisuli, then Pokhara, then I’ll know where to go from there.” He’d go on taking lifts, in one truck after another. True wandering should be without any regard for one’s destination, but that’s almost impossible to achieve.

The young baba was up before me in the morning, sitting in the sun, picking the seeds out of his grass. He told me about his itinerary of annual festivals while I spread my wet stuff out to dry. The weather seemed to have changed. The valley of the Trisuli River (which must be older than the mountains because it goes right through them) was below us to the left. Branching off it, curling around to the right as we looked north, lay the moon-shaped valley of Langtang.

There’s an idea in Tibetan Buddhism that Guru Rinpoche concealed certain valleys on the southern slopes of the Himalayas, called bayul, or hidden valleys, which would be used as refuges for good people in a future disaster. In the late seventeenth century, Langtang was identified as one of those bayuls. I’ve sometimes wondered how literally to understand the suggestion that in mountains like these, the presence of a whole valley might actually be unknown.

It was obvious from up here that for as long as people have been going to Gosainkund anyone could see where the Langtang Valley is. Neither is it safe from disasters. About 30,000 years ago one of the most destructive known incidents in the history of the world occurred in Langtang when an 8000-metre peak collapsed in an unimaginable convulsion, which displaced 10 cubic kilometres of rock and released such energy that stones turned to glass. That event had a minor sequel in 2015 when the earthquake shook ice loose from high in the cirque of mountains that remains from the first cataclysm. The ice swept down a hanging valley, gathering rock from glacial moraines. It lost contact with the ground as it hit the valley lip like a ski-jump, and crashed on to the community below with half the force of the bomb that destroyed Hiroshima. A woman whose name was Bhunti, whose place I’d stayed at a few years earlier, was getting married that day in Langtang. The shockwave in front of the avalanche was enough to obliterate the village, which was then instantly buried under many metres of debris that now covers forever the upper Langtang Valley.

I’d thought about going up there again this time. But a Langtang man I telephoned warned that the trails were still scoured by landslides, and the worst thing about them, he said, is that you can hear them coming through the forest but you can’t see them, so you don’t know which way to jump. That beautiful morning in Lauribina none of this was visible, and I noticed instead the curly wisps of cloud that clung to the mountains, which seemed to me exactly like the curly wisps of cloud that are shown in Tibetan paintings. I didn’t know at the time that that style of painting clouds is imitated from Chinese art, not from the Himalayan sky.

Excerpted with permission from Human Nature: A Walking History of the Himalayan Landscape, Thomas Bell, Penguin India.