ECO-Workshop entitled "Sustainable Cities and Waste Management: The Cases of Copenhagen & Samui Island" with participants from 6 countries (Thailand, Myanmar, Germany, Indonesia, India and Pakistan) has been organised on 24 November 2015 by Dr. Trakarn Prapaspongsa from Eco-Efficient Engineering Research Lab (ECO-LAB), International Graduate Programs in Environmental and Water Resources Engineering, Department of Civil and Environmental Engineering, Faculty of Engineering, Mahidol University. In this eco-workshop, a wide range of potential solutions have been discussed and presented. In conclusion, financial-based regulations (i.e. as eco-tax, entrance fee, increased fine for open dumping, etc.) are proposed as the most important tools for sustainable waste management on Samui island.