Flight Samui International Airport departs from Koh Samui Samui International Airport at 08:15 and arrives at Singapore Changi Airport at 11:10.
The flighttime is about 1h 55m. The distance travelled ("as the bird flies"): 475 Km. So the average speed is roughly 248 Km.
There is an 1 hour time difference between Koh Samui and Singapore
