Although Koh Chang is a relatively small island, you can still discover young trails that are completely untreated with a reasonable MTB. However, you should be heat-resistant, not afraid of cobras and not find spiders repulsive. Next year I will explore the hinterland of Ranong with a local, because there are supposed to be natural hot springs that are completely tour-free. It is possible that guided tours can be offered here. The demand seems great.
5 days ago