Overnight bus and train travel offer the most affordable options, with flights being the quickest and most efficient way to travel.
Best Chiang Mai to Koh Samui Flights, Trains, Bus & Ferry Times
It is, however, an amazing way to get across the two towns if you are on a time-strapped holiday. There are a couple of airlines that operate flights to Koh Samui, with a number of them making stopovers at Bangkok. The direct flight will take 1hr 45 minutes and will cost anywhere between $200-250 AUD each way. Other flights stopping in Bangkok can take between 3-5 hours (including stopovers) and cost between $100-200 AUD each way.
Travellers can also opt to take a bus or train from Chiang Mai to Bangkok, and then take a flight from Bangkok to Koh Samui. This shorter flight will only take 1 hour and will cost about $150 each way. A train is also another option from Bangkok to Surat Thani and they leave frequently and take around 14 hours to make the journey.
From Surat Thani, you will need to catch a bus from the train station to the ferry terminal, and a ferry to Koh Samui Island. The ferries are very frequent, leaving on the hour and only cost around 150 THB each way. The ferries will take around 3hrs to get from the mainland to the island (Nathon Pier).