The Caspian Sea is the largest enclosed inland body of water in the world, bordered by five countries: Russia, Kazakhstan, Turkmenistan, Iran, and Azerbaijan. Its unique ecosystem supports a variety of species, including the famous Caspian seal and several endemic fish species like the Beluga sturgeon. The sea's salinity is lower than that of ocean water, which influences the types of organisms that can thrive there. The Caspian Sea is also home to diverse habitats, including wetlands and coastal areas that provide essential breeding grounds for birds and fish. However, the ecosystem faces challenges such as pollution, overfishing, and climate change, which threaten its biodiversity. Conservation efforts are crucial to protect this unique environment and its inhabitants.