Koh Tao is located in the Gulf of Thailand just a short boat ride away from the bigger island of Koh Samui. There are a number of options for getting to Koh Tao depending on where you are coming from and your budget.
From Bangkok
We recommend the highspeed Lompraryah Catamaran company:
Alternatively for a direct flight from Bangkok to Koh Samui we can also recommend Bangkok Airways. You can always obtain a connecting flight with your original flight from your original destination and transfer from the Suvarnabumi Airport to Domestic Airlines.