At about two and a half thousand metres Doi Inthanon is the highest point in Thailand, and the road to the top is one of the few in the country where you will be wearing a jacket in the tropics. The mountain is the southern end of the Himalayan chain, and its slopes are covered by forest that changes with height, from teak and bamboo at the bottom through oak and pine to a cloud forest dripping with moss, orchids and tree ferns.
The road from Chom Thong climbs steadily, with a long series of curves, past waterfalls such as Mae Klang and Wachirathan, which throw a cooling mist across the tarmac, and through hill-tribe villages where Karen and Hmong farmers grow coffee and cabbages on terraced fields. The surface is good and well maintained, and the bends are open and smooth, but fog and rain can arrive suddenly. A fee is charged for entering the national park, and motorcycles pay a small amount. The top is often cold, sometimes close to freezing in the dry season, so wear layers.
Near the summit you will find two chedis, or pagodas, built by the Thai air force to mark the sixtieth birthdays of the king and the queen, set in a garden with views across the mountains. In the cool season, the gardens are full of flowers. A short boardwalk, the Ang Ka Nature Trail, loops through the cloud forest and a small bog, and it is a gentle, atmospheric walk. Birdwatchers come from all over the world to look for the rare species that live up here, from sunbirds to the green-tailed sunbird.
The best time is the cool season, from November to February, when the air is clear and the views reach far. The rainy season, from June to October, brings mist and slippery roads. Stalls near the top sell hot drinks, grilled corn and strawberries, and little noodle shops serve warming soup. This is the finish of a long climb, so take your time at the summit, drink something hot, and enjoy having reached the roof of the country.