The Chao Phraya Express Boat is the cheapest and most scenic way of getting to Khao San Road. If you're coming from the city centre, take the Skytrain to Saphan Taksin station, where you can transfer onto the express boat at Sathorn pier. Then ride the express boat all the way north to Phra Arthit pier, which takes about 35 minutes and costs 13 to 18 baht. Make sure to get either the orange flag line or the blue flag tourist boat, as the yellow flag line skips Phra Arthit pier completely. Use the map by the Express Boat dock to confirm operating times, and which flag-colored boats make which stops.