This paper focuses on the transboundary conflict surrounding water, its management, development and its impact on livelihood and culture of the communities residing in Sundarban delta of India and Bangladesh. Designated as a ‘Ramsar site’ this area is rich in biodiversity and is spread over 10,000 kms. Home to the world’s largest mangrove forest and with more than 2000 species, the site covers a large part of southern Bangladesh and southern part of West Bengal in India. However, this unique biodiversity is reeling under the threat of climate change and various associated factors that add to the vulnerabilities of people in both the countries inhabiting this land. They are among the poorest and most vulnerable people in South Asia. However, none of the two countries have incorporated the concerns of the local population in the transboundary management protocols around the Sundarban. Indo-Bangladesh friendship project of Rampal Coal Power Plant (2012) led to a large socio-ecological movement to save the Sundarbans from socio-environmental-economic exploitation. The cement factories in Bangladesh, industries in India near Sundarban are increasing the vulnerabilities of this region. Transboundary conflict over water in this region has resulted in the people getting affected by complicated international legal procedures as in this vast deltaic region, where the borders are porous. The paper argues that there is a need for sustainable resource management in the transboundary region of the Sundarban.