Uttaradit, Phitsanulok, Thailand - September 19, 2015: Trekking and Porter on the Mountain at Phu Soi Dao National Park, Uttaradit, Phitsanulok, Thailand Shutterstock Image - Uttaradit, Phitsanulok, Thailand - September 19, 2015: Trekking and Porter on the Mountain at Phu Soi Dao National Park, Uttaradit, Phitsanulok, Thailand - ID: 676948588