International Caspian Sea Day, observed on August 12, highlights the significance of the world’s largest enclosed body of water as a shared heritage among the five coastal nations—Iran, Russia, Azerbaijan, Turkmenistan, and Kazakhstan. This day serves as a reminder of the collective responsibility to protect the Caspian Sea’s unique ecosystem, which faces threats from pollution, habitat destruction, and climate change. The 2003 Tehran Convention was a pivotal agreement aimed at promoting environmental cooperation. Coastal states are urged to collaborate on protective measures, enhance scientific exchange, and educate future generations about the importance of preserving this vital natural resource.