Best would be to book an overnight bus to Bangkok Koh Tao. The night bus starts at 9 PM and reaches 5 AM in the morning. Lomprayah Bus Company is a good option to go. The buses go from Chumphon Station and Khao San Road. The bus and ferry combo cost 1400-2000THB. They also provide blankets and there is a TV to watch or disturb your sleep. The bus drops you to Chumphon pier, the ferry journey is 1.5 Hrs. to Koh Tao.
You have a van option available. They are cheaper at 1200THB. But I’ll avoid that.
Book your journey in advance, to have peace of mind that your seats are booked. Use 12go.asia as they offer to train, bus and ferry ticket booking online in advance.
Take any train from Bangkok to Chumphon. Take a ferry to Koh Tao. It is best to buy a Train and ferry ticket combo. This combo will cost you 1744THB. Chumphon is 485 Km from Bangkok and it takes around seven hours to reach.
1 = 1st class sleepers. S = 2nd class sleepers (air-conditioned). s = 2nd class sleepers (non-air-con).
2 = 2nd class seats. 3 = 3rd class seats. R = Restaurant car.
DRC = Diesel Railcar express with 2nd class air-conditioned seats, meals included, but no sleepers so not recommended for overnight journeys.
LC – Lomprayah Catamaran
KTC – Koh Tao Cruiser
SEB – Songserm Express Boat
KJCF – Ko Jaroen Car Ferry; NB = Night Boat
There are no direct flights to Koh Tao. However, fly to Chumphon, then bus to pier then ferry to Koh Tao. Nok Air flies from Don Muang airport in Bangkok. As always, buy a combo deal flight, shuttle service, and ferry.