Wachirathan Waterfall

This is the one people remember from a Doi Inthanon day trip, and it earns it. Wachirathan, the diamond stream in Thai and once called Tat Khong Yong, drops in a long white curtain about 750 m above sea level and hits hard enough to throw mist across the whole clearing, so you'll get damp just standing there. Come in the morning and the sun through that spray throws rainbows across the rock.

It's at km 21 of Route 1009, the road to the summit, 13 km past the park's main checkpoint at km 8, which puts it roughly 80 km from Chiang Mai by Highway 108 and then the 1009. A side road of about 500 m leads to the parking lot. You can see the cascade from there, and a short paved path with steps drops to two viewing points at different distances, so you choose how wet you get. Allow 20 to 30 minutes. It's a waterfall for looking at, and swimming isn't allowed. There are toilets, small restaurants and coffee stalls by the parking lot.

There's no separate ticket. You pay the Doi Inthanon National Park fee at the km 8 checkpoint, in cash, ฿300 for foreign adults and ฿150 for children aged 3 to 14, ฿60 and ฿30 for Thai visitors, plus ฿30 for a car or ฿20 for a motorbike. The falls are open 06:00 to 17:00. July to October, when the rains push the flow to its peak, is when it's at its loudest, and from February to April it thins out a lot.

Treat it as a stop on the way up or down the mountain rather than a destination in itself. Most Chiang Mai day tours to Doi Inthanon stop here, and tour groups roll in through the day, which is the main argument for arriving early. The steps get slippery from the constant spray, so wear shoes with grip and bring a cover for your camera.