The increase in harmful algal blooms (HABs) in the seawaters of India can be attributed to multiple interrelated factors including the discharge of nutrients from estuaries, land run-off during monsoons, and upwelling in seas. Nutrient discharge, primarily nitrogen and phosphorus from agricultural runoff and waste effluents, fuels algal growth, while monsoon run-off carries additional nutrients into coastal waters. Furthermore, upwelling brings nutrient-rich waters to the surface, creating ideal conditions for algal proliferation. Together, these factors contribute to the frequency and intensity of harmful algal blooms, which can have significant ecological and economic impacts.