The Bay of Bengal has never been simply water. It is an opera of commerce, travel, and geopolitics. In it, 54 rivers transport not only their rich silt, but centuries-old grievances, and 4,156 kilometres of borders make neighbours into threats to national survival. However, among all the actors shaping this region at present, the most important may be one that did not occur in a military command centre, nor in a diplomatic negotiating room, but at a ballot box in West Bengal.