Oceanographic and Marine Science Perspectives on the Caspian Sea: A Comprehensive Review

The Caspian Sea, the world’s largest enclosed inland water body, represents a unique ecosystem of profound scientific and geopolitical importance. Situated between Europe and Asia, bordered by Russia, Kazakhstan, Turkmenistan, Iran, and Azerbaijan, it displays hybrid oceanic and lacustrine characteristics that have fascinated marine scientists for decades. This review synthesizes contemporary research in oceanography, marine chemistry, hydrodynamics, and ecosystem dynamics of the Caspian Sea. It explores the physical structure of its three basins, salinity gradients, thermal stratification, and circulation patterns, while also addressing major environmental challenges including pollution, overfishing, and sea-level fluctuations. Emphasis is placed on the regional and global implications of anthropogenic pressures and climate change, which continue to reshape the hydrological and ecological balance of the Caspian Sea. The findings highlight the critical need for coordinated transboundary monitoring and sustainable management strategies, supported by advanced oceanographic modeling and satellite-based observation systems. Keywords: Caspian Sea, oceanography, marine science, hydrodynamics, ecosystem, salinity, climate change, pollution.