My description of the Mae Hong Son Loop will assume a trip on public transport from Chiang Mai to the north till Mae Hong Son, and from there, to the south and back to Chiang Mai through Mae Sariang. It will be hard to avoid Chiang Mai as the starting point of the trip, but the direction taken was almost random. The only reason to begin with the north is that if you are pressed for time, then the northern path is more mountainous, scenic, and shorter. In Chiang Mai, you should arrive very early to the Arcade Terminal. Despite the weird Romanization of the Thai, you should pronounce it Akaed; otherwise, you won’t be understood. Any songthaew in the direction will take you there for 10 Baht (usually they ask more from tourists – but that is the price). The regular bus to Mae Hong Son through the 270km-long northern route (road 1095) leaves at 7am, arrives around 3pm, and costs 105 Baht. Two hours after departure, you may refresh yourself at Ban Mae Sae, and within another 2 hours, you will arrive to Pai.
This small town hosts an incredible number of tourists, which sometimes outnumber the locals on the streets. It is a popular site to start treks from, but since the town sits on the flat banks of the River Pai, you have gained almost nothing by relocating yourself here from Chiang Mai. If you want to leave yourself that option open, you can break here your journey and continue after having explored the place. The bus stops here for a relatively long break that allows you to try a coffee in one of the nearby fashionable cafés. Around 1pm, the bus arrives at Soppong, from where there is access to the Tham Lot Cave, which hosts a subterranean stretch of the Lang River. If you want to explore the cave, you should continue 9km to the north to Ban Tham, where there are suitable commodities for spending the night over. If you stayed with the bus, roughly 2 hours after Soppong, you will reach Mae Hong Son after having travelled through a beautiful and mountainous area. From here there are buses back to Chiang Mai through the two routes.
If you are short on time and want to return in the same way, there are two air-conditioned buses, the first is a minibus leaving at 8am, and the second, a regular bus at 9am. Both cost 200 Baht. Regular buses leave at 7am, 8:30am, 10:30am, 12:30pm, 2pm, and 4pm, and cost 105 Baht. If you are planning to close the loop, then you should know that the southern leg is longer, 368km, and thus it is recommended to break your trip at least once in Mae Sariang, 166km south from Mae Hong Son. The same buses serve both options. Air-conditioned buses leave at 6am, 10:30am, and 1pm and cost 140 Baht to Mae Sariang and 261 Baht to Chiang Mai. The last bus is not recommended, since you won’t be able to see the beautiful way. Regular buses leave at 8am, 2pm, 8pm, and 9pm, and cost 78 and 141 Baht respectively. The southern part is less steep, thus the bus travels faster and soon you will find yourself back on the plains. The forests along the way are not deserted, and from time to time, the bus will stop for the sake of people suddenly appearing from the woods.
Around 2 hours and 71km later, you will arrive to Khun Yuam, a cute village where you can break your trip at Ban Farang Guesthouse, just a little after the central ‘Y’ junction. The bus makes a long stop here. After a couple of hours and after crossing Mae La Noi, Mae Sariang will be reached. It will be a sin not to stop for a while in this relaxed town built between the Yuam and Mae Sariang Rivers. By the Yuam River there are several guesthouses and restaurants. The Riverside View Guesthouse is a pleasant and typical Thai wood structure sitting along the river; it has a nice restaurant in its big balcony, which is suspended by columns over the waterfront. If you left with the earliest bus from Mae Hong Son, then you arrived here exactly at the perfect timing for a late breakfast or a festive brunch over the river.
If you are staying here for a few days, you can make a return trip to Mae Sam Laeb, a tiny village on the border with Myanmar, 46km southwest from Mae Sariang, on the Salawin River. Trucks to there leave from the market at irregular times. To finish the classical loop, you can continue from here to Chiang Mai, but the town location opens the option of a "bigger-loop" variation by continuing south for a farther 162km to Mae Sot. There is a truck leaving at 12:30pm and arriving at 6pm; it costs 160 Baht due to the bad conditions of the road. In the midway, you exchange truck with one coming from Mae Sot, so that each crew returns home at the end of the day.
Before and after the huge Burmese Refugees Camp, the Thai Army will check your passport and register your details; you are not allowed to delay there. At the camp, huts populate densely the hillside with their roofs of big, dry, and folded "elephant" leafs. Mae Sot has a border cross to Myanmar, where you can renew your Thai visa, but that and a proper way to end the Big Northern Loop will be described in other entries. Don’t forget that despite the density of information in this entry, it is not intended to be done without stops; you should take this trip easily and have some sanuk (fun).