The Duke and Duchess of Cambridge are due to fly from India to the remote Himalayan kingdom of Bhutan.
Over the next two days the couple will meet the country’s king and queen and trek up a mountain to visit the famous Tiger’s Nest monastery.
They will also receive a ceremonial welcome and watch a competitive game of archery, the kingdom’s national sport.
William and Catherine are in the middle of a seven-day tour of India and Bhutan.
After arrival in Bhutan on Thursday, the royal couple will have a private audience with King Jigme Khesar Namgyal Wangchuck and Queen Jetsun Pema, as well as a private dinner with them later on.
Bhutan: A land of revered royalty, tree-planting and happiness
BBC royal correspondent Peter Hunt
The descent by plane, which has to navigate a mountainside, is not for the faint-hearted.
William and Kate are entering a once isolated land.
Tourists could only visit from the 1970s; TV was introduced in the ’90s; and this former absolute monarchy became a constitutional one with an elected government in 2008.
Bhutan is a Buddhist country with an emphasis on gross national happiness rather than its gross domestic product.
However, the country’s prime minister has acknowledged that this much-lauded concept can be overused, and can mask the kingdom’s problems with debt, unemployment and poverty.
For two days the Cambridges will be guests of a young king and queen that are held in high regard by its subjects.
They’ll learn how Bhutan – which once revelled in its remoteness – is now facing the challenge of how to retain its Buddhist traditions while also embracing the modern world.
On Wednesday the pair toured Kaziranga National Park in the state of Assam in an open-topped 4×4, catching sight of elephants, monkeys and a monitor lizard.
They later visited a village on the edge of the park to find out how villagers live side-by-side with the wild animals.