If you want to travel between Malaysia and Thailand using public transport, then the Padang Besar Border is the best place to go to if you are heading to or from either Penang, Langkawi or Kuala Lumpur from or to Hat Yai in Thailand.
There is another border checkpoint at Bukit Kayu Hitam / Sadao, but that offers no chance for public transport, with the nearest bus stopping at Changlun in Malaysia, some 8 kilometres from the border.
The only way to get to Changlun from Bukit Kayu Hitam is by taxi.
So, to save money and do it all by cheap bus, head to the Padang Besar.
For those that just want to get to Penang as quick as possible you can get a minibus from Hat Yai which crosses into Malaysia at the Sadao / Bukit Kayu Hitam border crossing, then travels down highway 1 straight to Penang.
Another option is to travel by train between Hat Yai and Butterworth.
It is fairly slow compared to the minibus, but more relaxing, with more to see along the journey.
You can reach the border by local bus from Hat Yai or buses from towns south of Padang Besar in Malaysia.
At the border, simply get your passport stamped out of Thailand, then walk straight for about 100 metres and turn right down the hill.
The walk in no man's land is not too far and is easily done in 5 - 10 minutes. Otherwise you can hire a motorbike taxi to do the trip, but for most people it is not really worth it.
On the way you can drop into the fairly large duty free shopping outlet half way down the hill. This place is very popular with Malaysians as they can stock up on cheap booze and cigarettes, which are much more expensive in Malaysia than they are in Thailand.
They also sell a wide range of other duty free goods, such as perfumes, watches, baggage, chocolates and clothing.
When you get to the bottom of the hill, the Malaysian border checkpoint is on your left. Take the first road in and go to the first booth on your left.
There are no forms to fill in and most Nationalities get a 90 days entry visa.
you are going the other way into Thailand you have to get a form first
from the booth and fill it out. You will only get a 15 or 30 days visa, unless
you have obtained a visa beforehand at a Thai embassy or consulate.
You can get one in Penang at the Thai Consulate.
When you leave the border area you will now be in Padang Besar Malaysia. Just outside is a large roundabout with flagpoles. Keep to the right and walk around, then straight ahead to the bus stop.
The Padang Besar train station is also close by. There are stairs that lead up and over the tracks on your right, just after you get you passport stamped into Malaysia.
There is a money changer here, but he would probably only be open when trains come in, so it is best to have changed a small amount of money up before crossing the border.
It is also possible to catch a train from Padang Besar rather than the bus.
I would not bother about catching a train from Padang Besar to Hat Yai as it is very expensive for the short distance.
The border is open daily from 06.00 until 22.00