The quickest and most convenient route from Penang to Hat Yai would be the minivans/buses crossing the borders from Malaysia to Thailand at Dannok (Sadao). These minivans/buses leave relatively regularly from the terminals at Penang Komtar in Georgetown, a tower/building which can be seen from pretty much anywhere in Georgetown’s tourist zone (minivans normally leave at 08:30, 12:00 and 13:30 timetable here). The minivans/buses leave from the tour offices found outside the building, but there is a rather massive air-conditioned mall inside Komtar, which is perfect to eat and kill any extra time. From Penang to Hat Yai it should then be, hopefully, around 4 hours, but this will depend on a number of factors.
Dannok/Sadao Border Crossing
It should take around 4 hours for travel between Penang and Hat Yai, however, these travel times should be taken loosely, as the last time I travelled on a Friday evening I didn’t arrive to Hat Yai until after 10:00PM (7 hours). When I was first held back by rush hour traffic leaving Penang, and then there were visa troubles with other passengers at the border crossing (outlined below). Otherwise the border crossing from Thailand to Malaysia should be relatively simple, as it is a quick stamp out of Malaysia (Dannok), and then a stamp in on the opposite side in Thailand (Sadao). Although something I did find strange was during a minivan fuel-stop when the driver and his chum asked us to pay for Thai immigration cards (I think it was 10 Baht or s0) which is very much illegal (given they are distributed government documents) and they are of course free and plentiful when arriving to the border.
‘Visa on Arrival’
Most western nations will be given a 14-day stamp (visa exempt) in Thailand, meaning visas are not necessary for short stays in Thailand. However, if planning to stay longer, and need a visa to do so, the visa application must be completed at the visa offices in Georgetown Penang (or any Thai Embassy really). As visas cannot be issued at the border (below right are similar travel prices/destination from outside the Thai Embassy). However, if crossing the border with a Thai visa, it is best to have copies of any documentation used during the original visa application. E.g. copies of onward travel and sufficient finance to cover your stay in Thailand. It may also be best to have similar copies of finance and onward travel, even when crossing for the visa exempt stamp (to be safe). Otherwise the crossing should be free and easy, and I was stamped within minutes and was the first to cross the border from our minivan. But I then had to wait 40 minutes for some South African lad to get proof of finance (a printout from an ATM) as well as a Filipino family who offered a bribe to border control to make the crossing easier (the irony).
Alternative and Onward Travel
Normally I would travel from Penang to Hat Yai by train, only this route was recently complicated with the upgrade of Malaysia’s train lines, meaning a transfer between lines became necessary at the border (Padang Besar). However it is still easy to jump on the trains from Hat Yai when travelling north towards Bangkok, which I will always prefer to coach and minivan journeys (I do enjoy trains). But it will always be a good 12 plus hour journey to Bangkok by either of these options. So, with low-cost carriers these days, it can be cheaper to travel on flights from Hat Yai’s airport to various destinations throughout Thailand, and my last flight to Chiang Mai was little more than 800 Baht (it would be double that by road). Otherwise it is relatively easy to find onward travel from Hat Yai by minivans/buses to the islands and other various destination throughout Thailand. I also prefer an overnight stay in the city and Hat Yai central hotels are found here.
Do Not Bribe Officials
An obvious statement, but my last crossing from Penang to Hat Yai was otherwise confused by some Filipino bloke travelling with his Thai wife and young daughter, who told the minivan passengers to put a 100 Baht note in passports for the border control (do not do this). But it just confused everyone. “So we have to pay 100 Baht to cross the border”, “No, it’s a present for border officials”. “Is that not corruption? So the border officials are corrupt?”. “No, it’s a present. It’s normal here”. It is most definitely not normal here. Yet he kept going on about it “Don’t forget to put 100 Baht into your passport” and he even approached people individually. Which is when I told him “I’ve done border crossings for 9 years now, with no problems at all. And I’d sooner turn around at the border than bribe corrupt officials”. Dickhead. He even tutted when a guy questioned the illegal immigration cards sold earlier: “tut, it’s only 10 Baht”. Anyway, I don’t know if this is a Filipino thing, or the guy was just a twat (or both), but he really did epitomize everything that was wrong with these parts of the world. And was teaching his young daughter to do the same.