Istanbul with a population of more than 14 million is one of the most populous megacities of the world. Standing on two peninsulas, coastal historical megacity is a tourism and financial centre for Turkey. It examines rapid urban development and an excessive amount of migration. Standing at the south of Istanbul, Sea of Marmara holds nine islands with a history dating back to ancient times. Only five of these islands are inhabited ones. This study focuses on the Buyuk Island, which is the official centre of these islands and capable of capturing majority of the cultural and natural heritages. With an area of 5.4 kilometres square, the Buyuk Island is the biggest island existing within the Princes' Islands System which hosts 140,000 tourists during the summer seasons.