Skimboarding (also called skimming) is a beach sport with a board, usually in wood, used to glide on the water's surface. Skimboarding starts by running on the sand, dropping the board onto the thin water from previous waves, jumping to the board and for the best riders, sliding to the waves, performing a few tricks, and coming back to the shore.
(Pictures: CLA Skimboard Thailand)
Sand skimming is the best for beginners, you just need a flat beach. Wave skimming needs more experience and beaches with steep slopes and strong shores.
White Sand beach and Klong Prao beach are the best beaches to practice sand skimboarding. For wave skimming, Kai Bae beach and Lonely Beach would be better but during the rainy season when there are nice waves.
Once you've found the beach, you will need a board. Unfortunately, nobody is renting skimboards on Koh Chang. Hopefully, it will come but if you see a skimboarder, you can always ask if he has a second board you could loan.
The day there will be a place where to rent skimboards, I will add it to this page.