Koh Tao is a small island of approximately 21 km² and receives over a 100,000 visitors per year. To minimize your impact on the eco-system, notice that there are no garbage disposal facilities, so everything that can't be burned has to be taken away. Try to avoid plastic bags that are given out for every purchase you make. There is also no department to clean the roads or other public areas, so don't dump your waste on the open landscape. Water is scarce and electricity expensive, so don't waste them.