Good news for those, who love run shot  running in Thailand. Koh Samed Half Marathon will took place in 17 sep 2017 on Koh Samet island.
Koh Samet - beautiful island 6 km far from the Rayong. You can book rooms in Rayong and go to the island only for participation in half marathon
You can register  just  before start on start place. You can reach island from Bangkok ( Ekkamai metro station) by bus (100 ThB) 

FaceBook Page of Ko Samet Half Marathon