Bus Buses and taxis can be taken from the west or east coasts of peninsular Malaysia to destinations within Thailand. Crossing the Thai border by public bus from the west coast can be tricky. Buses on the main highway terminate at Changlun, a small and isolated Malaysian town some 20 km from the border. Travelers going overland can also take a bus or train to Padang Besar, where buses and taxis continue to Hat Yai. You'll need to walk over the railway bridge into Thailand, ignore the unofficial taxis and motorcycle taxis at the end of the span, and continue walking until you reach the 'official' taxis a few hundred meters beyond the end of the bridge.
Official taxis carry a posted government permit near the meter.
These taxis will take you to Hat Yai with a brief stop for border formalities at Thai immigration. Direct buses can be booked through travel agents in Penang or picked up at terminals in Penang, Butterworth, and Hat Yai. Public transport on the east coast of peninsular Malaysia is fairly straightforward. Bus 29 departs each hour on the hour from the main bus terminal in Kota Baru and 20 minutes later reaches the Malaysian border town of Rantau Panjang. You then walk across, conduct border formalities with Thai immigration, and catch a tuk tuk for B10 to the train or bus station in Sungai Golok.