For decades, the only foreign visitors to venture into Papua were gold-diggers, anthropologists, missionaries and soldiers fighting imperial wars.

But the vast, western half of New Guinea island is slowly opening its doors to tourists as a “hidden paradise”, a land of ancient tribal cultures, glittering reefs, soaring glaciers and teeming wildlife.

Recreational travellers are still few, at most a few thousand a year; people like Sarah Gabel, a 29-year-old American who says she is “captivated by people who live in harmony with nature”.

That’s what she found in the Baliem valley, the long-isolated home of the Dani tribe high in the Papuan central highlands, outside the town of Wamena.

This kind of “ethnic tourism” has become the main market for New Guinea, the largest island in Asia, where a thousand indigenous tribes are divided between the independent state of Papua New Guinea to the east and the Indonesian-controlled provinces of Papua and West Papua to the west.

Packed with exotic wildlife, Papua also attracts nature buffs and ornithologists in search of birds of paradise and cockatoos. Environment group WWF this week announced the discovery of more than 1,000 new species on New Guinea, including a frog with fangs and a round-headed dolphin.