Much has been discussed about the potential that hydropower has to foster socioeconomic development in countries in South Asia, mainly among Bangladesh, Bhutan, India and Nepal, also known as the BBIN countries. Given the vast renewable hydropower potential of Bhutan and Nepal, development of hydropower and cross-border interconnections have the potential for the four countries to improve energy supplies, promote navigation, alleviate floods and encourage connectivity, and add significantly to socioeconomic development. Improved regional cooperation can benefit the millions of people in the region who live in extreme poverty and whose lives can be improved with initiatives that support economic growth (Dhakal et al., 2019b; Srivastava & Misra, 2007). Collaboration among the countries in the region for inter-and intra-regional energy trade has been identified as the most cost-effective way to address the growing demand for energy, including increasing the supply and diversification of sources (Rahman et al., 2011; SAARC Secretariat, 2010). At present, energy trade in South Asia is limited to India and Bhutan, India and Nepal, and India and Bangladesh (United States Agency for International Development (USAID), 2017). Collaboration has been encouraged with regional cooperation, first with the SAARC framework (South Asia Subregional Economic Cooperation, 2016) and then with BIMSTEC (https://bimstec.org/). Countries in the region share strategic interests that go beyond hydropower development and which include development cooperation, political stability and good neighbourly relations. One example is Bhutan and India, where Bhutan's economy is tightly tied to its political relations with India, just as India's energy security needs (mainly in the northern states) are significantly fulfilled by Bhutan. The strategic importance of Bhutan for India is immense: the countries share strong economic linkages; Bhutan acts as a buffer zone between India and China; and Bhutan has lent support to India on numerous occasions, including security treaties in the case of the Indian northeast states. They have represented landmarks for the close collaboration of both countries in maintaining peace and security in the region, including energy security (Tortajada & Saklani, 2018). Examining technical but also political dimensions is crucial for understanding complex relations that are intimately tied with opportunities for cooperation on mutually beneficial areas. This special issue includes papers presented during a workshop organized by the