This chapter supports UN SDG 13 (Climate Action), SDG 14 (Life Below Water), and SDG 3 (Good Health and Well-Being) by examining global trends and complex drivers of harmful algal blooms (HABs), which are influenced by climate variability and environmental changes. By highlighting the need for integrative research to understand and mitigate HAB outbreaks, it contributes to protecting marine ecosystems and reducing health risks associated with algal toxins.