If you want to travel from KL's main bus station, Terminal Bersepadu Selatan, TBS to Hatyai in Thailand, you have a choice of taking a bus, or a faster Electric Train Service (ETS), then a Shuttle service from the border, or fly from nearby KUL Airport to HDY.
The bus is the cheapest way to travel from TBS to Hat Yai, with tickets costing between 50 to 60 RM.
A popular way to travel is to take and overnight bus to Thailand from TBS.
The duration of the journey is around 8 hours, but this depends on traffic and how long it takes to go through all the border formalities / passport control.
Although the train is more expensive than the bus, it is a much nicer way to travel and you get to see more of the countryside from the train window than you do from the bus.
From TBS to Hat Yai Junction railway station, you will first have to take an ETS train from Bandar Tasik Selatan railway station (connected to TBS bus station by footbridge) to the border station of Padang Besar.
There is however, currently only one train a day from BTS / TBS to Padang Besar.
Tickets prices for the ETS TBS to Padang Besar cost 77 RM for adults - 43 RM for children.
Another option is to take the short KTM Komuter or KLIA Transit train from BTS to KL Sentral Station.
From KL Sentral there are more frequent departures to the Thai border.
Once you reach the border, you will have to go through passport control at the station (if you want to continue your journey to Hat Yai by train), then you can take one of the Shuttle train services from Padang Besar to Hat Yai.
If your ETS does not connect to the Shuttle to Hat Yai, you can cross over in to Thailand by the main road border located next to the train station.
Once in Thailand, you can then continue your journey by local bus or minivan to Hat Yai.
The quickest option to get from TBS to Hat Yai is to fly from KUL to HDY.
Air Asia now have regular flights to Hat Yai and you can get some good deals if you book in advance.
From TBS to KLIA / KLIA2, you just take a quick KLIA Transit train to the airport.
The airport in Hat Yai is located a few km south of the city and you can easily get from the airport to the city centre by shuttle bus or taxi.