Why is Caspian Sea a lake and not sea?

The Caspian Sea is considered to be the largest inland body of water but is often misunderstood as a lake or a sea due to its lack of connection to an ocean. This classification debate is based on various factors, including its size, salinity, and geographical location. Here are the reasons why the Caspian Sea is generally regarded as a lake:

1. Landlocked: The Caspian Sea is entirely landlocked, meaning it doesn't have a direct connection to any oceans or open seas. It is surrounded by five countries: Russia, Kazakhstan, Turkmenistan, Iran, and Azerbaijan.

2. Lack of Oceanic Connection: Unlike true seas, which are connected to oceans and experience tidal influence, the Caspian Sea is hydrologically isolated. It does not have a direct outlet to the global ocean system, making it a closed basin.

3. Freshwater Inputs: The Caspian Sea receives significant freshwater inflows from several rivers, including the Volga River, the Ural River, and the Kura River. These rivers contribute a large amount of fresh water, diluting the salinity levels in the sea.

4. Variable Salinity Levels: The Caspian Sea's salinity varies across its surface and over time. The northern regions are less saline due to the significant freshwater inputs, while the southern parts have higher salinity levels. The average salinity of the Caspian Sea is approximately 13 parts per thousand (ppt), which is considerably lower than the salinity levels of most oceans (around 35 ppt).

5. Geological History: The Caspian Sea is a remnant of the ancient Paratethys Sea, which was connected to the global ocean millions of years ago. However, over time, tectonic shifts and changes in sea levels isolated the Caspian Sea from the ocean, transforming it into a landlocked lake.

It's important to note that the term "lake" or "sea" is not always strictly defined in scientific terms and can sometimes depend on cultural, historical, or geographical contexts. However, based on its geographical characteristics and hydrological features, the Caspian Sea is broadly classified and recognized as a lake rather than a sea.