Even if you don't plan any mountain trekking in Bhutan, you will have to make some ups and downs along the way as almost the whole country's territory is a collection of hills and mountains. For those who are ready for conquering some Himalayan peaks, Bhutan is a perfect destination.
The first thing you need to know about the mountains in Bhutan is that it is prohibited to climb the peaks that are higher than 6,000 metres. It is because sacred deities inhabit those places and humans shouldn't bother them, or because Bhutan doesn't have decent rescue services, but today we can only observe the beauty and might of those mountains from a distance.
There are plenty of treks in Bhutan, for a one day trip or the whole month. Some are aimed to come as close as possible to one of the 7,000 meter peaks, like the Jomolhari trek. Others may circle around ancient temples or help you to explore the nature of protected areas, like the Merak Sakteng Trek. When choosing your own option, pay attention to the length of the trek and the altitude.
The best time for hiking and trekking in Bhutan is from mid-March to mid-May and mid-September to mid-November, as this is when the weather is favourable and nature is in bloom with various colours.