The Caspian Sea is rapidly shrinking due to a long-term decline in water levels, primarily driven by climate change and habitat degradation. Satellite observations and hydrological research indicate a consistent downward trend since the mid-1990s, affecting ecosystems, biodiversity, and coastal communities. The main freshwater source, the Volga River, is experiencing changes in discharge, exacerbated by rising temperatures and increased evaporation. The decline is impacting species like the endangered Caspian seal and altering human activities, particularly fishing. Regional cooperation under the Tehran Convention aims to address these environmental challenges.