From Bangkok, the easiest option is to catch a direct internal flight to Koh Samui (50 mins approx) and then a short 30 minute ferry trip to Koh Phangan.

There are also many tourist buses running with a connection to a boat running from Khaosan road. This is the cheapest way to come to this island. Also it is coming here by night train is very popular. The trains arrive at Surat Thani station in early morning. At the train station, a joint ticket, a bus to Donsok + a boat to this island, available.