More than 200 people – about 100 of them abseilers – formed the search team that also included park rangers, police, military officers and rescue workers.
They are focusing on an area on Phanthurat Mountain, where mobile-phone signals of the missing tourist – identified as 34-year-old Gollino Cyrit Tizzlano – were last detected.
At about 10pm on Wednesday, some local residents reported hearing the sound of wood tapping in that area, but a two-hour-long search failed to find the missing tourist.
Before he disappeared, Tizzlano reportedly offered a local 2,000 baht to help him look for his lost drone. However, the local declined the offer because it was getting dark.
The search area is in difficult terrain marked by high limestone cliffs and slippery elevations due to rain.
Tizzlano checked in at Khao Sok Holiday Resort last Friday. The following day, he ventured into the forest alone with his drone after declining the offer of a guided tour.