I kept thinking it was the sea; it’s so vast. Set at an altitude of 3,810m, and measuring some 190km by 80km, Lake Titicaca is by far the biggest high-altitude body of water in the world.

Chugging out on the motorised ferry from Copacabana, it felt as though we were starting an epic voyage, and in some ways we were, for we were travelling to the sacred centre of the ancient Andean world. For the Inca, this was the birthplace of their dynasty and the place of the creation of the sun and the moon.

The Isla de la Luna is small. We climbed stone steps to Inak Uyu, a temple formerly dedicated to the moon and staffed entirely by women; and at the edge of ancient Inca agricultural terraces, we found a little bit of paradise. Two or three adobe huts, thatched with grass. No electricity, just a thin mattress on a raised mud platform, and a wooden bench and table outside. We chatted to Felix, the caretaker, who’d lived on the island all his life. When he heard we’d been in La Paz, he shook his head – ‘too busy, too many people’, he said. He said  exactly the same about the Isla del Sol. On the Isla de la Luna there are just 23 families, 82 folk. A map of the village at the boat landing showed little more than two football fields. We sat at the rustic wooden table while we waited for lunch. One of the womenfolk of Felix’s family spread a brightly-coloured woven cloth. We were given a bowl of potatoes as an hors d’oeuvre – sweet potatoes, and knobbly, nutty tasting, long, thin potatoes. Titicaca fish and more potatoes and rice followed. In front of us the marvellous mountains and in our ears, the sound of Titicaca lapping the pebble beach below. A woman washed clothes in the lake, and spread them on the stones to dry, her skirts looking like a new form of sea-life, beached and stranded. A small dog sat at her heels.

After lunch we walked, stopping often to listen to the quiet. It was mystical and magical. We came across a Buddhist monk on the beach, sitting cross-legged, a maroon habit around his shoulders, a conical shaped, tasseled woolly hat on his head. He told us he’d been meditating for five days. It was that kind of a place. We walked to the town, and up over the ridge. Rocks, blue sky, the smell of eucalyptus, and the temple below. A man herded llamas. A woman raked the earth with a hoe. An older woman struggled up hill, a bundle on her back, tugging four sheep on a rope. They were reluctant to move, wanting only to eat. After dinner (more fish, more potatoes, more rice) we were completely alone. The 82 were in the village on the other side of the island. After sunset, when the mountains were no longer visible, we watched the stars. Silence and darkness. Contentment and comfort.

The next morning the wind was up, and the water was white-capped. The mountains were hazy, grey, lilac-tinged tips, rising out of the water. Always present if not always visible. A hydrofoil tried to dock, but failed. We were awaiting the arrival of the daily ferry, and wondered if we would be able to leave. When the boat took us away, we didn’t know whether to be happy or sad. But the Isla del Sol was almost as enchanting as the Isla de la Luna.

We stayed at Challapampa, much quieter, much less visited than the touristy south; in a hostel between two sandy beaches, where locals took their cattle, pigs and sheep to drink, collected and raked green sea-weed for animal fodder, and men fished in brightly-painted wooden boats. We walked to Inca ruins, and climbed little peaks for views of sparkling blue water, rocky coves and sandy bays; old stone houses, shepherds, and men and women carrying gigantic bundles of animal fodder. Time seemed to stand still here. Mountains meshed with cloud, sea with air, so that we felt tiny, indistinct, but connected to the whole.