Samui police were alerted of the fatal accident on the uphill road in Ban Mae Nam village in Tambon Mae Nam of Samui district at 6.30pm.
The tourist was identified as Zurab Dzhakhua. He suffered a severe head injury after his head hit a rock a deep ditch, police said.
Friends told police that Dzhakhua was riding a rented motorcycle alone to take photos of the sunset from the top of the mountain road but his motorcycle somehow fell into a ditch on the roadside.
Police suspect he lost control of the bike while riding the steep road.