With its network of rickety staircases and walkways built in, on and around a giant sandstone outcrop, Wat Phu Thok is one of the region’s wonders. The precarious paths lead past shrines and gù·đì (monk's huts) that are scattered around the mountain on cliffs and in caves and provide fabulous views over the surrounding countryside. A final scramble up roots and rocks takes you to the forest on the summit, which is considered the 7th level.
If you hustle and take all the shortcuts you can be up and down in about an hour, but we advise against it: this is a climb that should be savoured. The quiet isolation entices monks and mâa chee (nuns) from all over Thailand to come and meditate here, so remember to be quiet and respectful as you explore.
Monastery founder Luang Pu Juan died in a plane crash in 1980, along with several other highly revered forest monks who were flying to Bangkok for Queen Sirikit's birthday celebration. A marble chedi containing Luang Pu Juan's belongings, some bone relics and fantastic exterior sculptures sits below the mountain amid a lovely garden.
Túk-túk in Bueng Kan ask 1000B (this is negotiable) for the return journey to Wat Phu Thok, including a few hours of waiting time. It's cheaper to take a bus from Bueng Kan to Siwilai (20B to 30B, 45 minutes), where túk-túk drivers will do the trip for 400B. If you catch an early bus to Bueng Kan, Wat Phu Thok can be visited as a day trip from Nong Khai, although there's no need to backtrack since you could also just catch one of the vans or buses running from Bueng Kan to Udon Thani.
If you're driving or cycling, continue past Bueng Kan for 27km until you reach Chaiyaphon, then turn right at Rte 3024, the road signed for Chet Si and several other waterfalls. (These are in the Phu Wua Wildlife Sanctuary and make worthy detours, as much for the weird rocky landscape as for the cascades. There's only water from mid-May through December.) After 17.5km make a right and continue 4km further.