Doi Inthanon rises to 2,565 metres, the highest point in Thailand — high enough that frost silvers the summit meadows on winter mornings and the air slips below freezing. That is startling in a country better known for tropical heat. The mountain is a granite mass at the southern tail of the Himalayas, and the landscape changes as you climb it. Humid lowland jungle gives way to temperate cloud forest, its trees draped in moss and hung with orchids, then to open grassland where rhododendrons bloom. The summit itself is a peat bog choked with sphagnum moss and ferns, the coolest, dampest ground in the country. Some 500 bird species live across those bands, which makes Doi Inthanon the richest birdwatching ground in Thailand, with Himalayan species found almost nowhere else in the country. The mountain is named for Inthawichayanon, one of the last independent princes of Chiang Mai, whose ashes rest in a stupa near the top.
The road to the summit winds past the thundering Wachirathan waterfall and through Hmong and Karen villages on terraced hillsides. Those slopes grew opium poppies into the 1970s; the crop that replaced it was coffee, and it is now the mountain's other export. Near the top, terraced flower gardens spill toward a horizon of layered ridges. Dawn is the moment to be here. Walk the Kew Mae Pan trail to the cliff edge and watch the sun flood the waking valleys with pink, with the ridges of northern Thailand floating above a floor of cloud. It is cold enough at that hour to see your breath. A local guide is required on Kew Mae Pan, and the trail closes through the rainy months when the slopes turn to mud. A national park guards the whole mountain, and you can drive to within a few steps of the summit sign.