The Caspian Sea is technically neither purely freshwater nor fully marine; instead, it is considered a brackish body of water. While it’s often referred to as a “sea,” it is actually the world’s largest enclosed inland body of water, with no direct outlet to the world’s oceans.
Its salinity is lower than that of ocean water but higher than typical freshwater lakes. On average, the Caspian Sea’s salinity is about one-third the concentration of the open ocean—roughly 1.0–1.2% compared to seawater’s approximate 3.5%. This moderate salt content comes from various rivers (notably the Volga) flowing in, and from the gradual accumulation of salts that do not drain out due to its landlocked nature. Additionally, salinity levels can vary by region, with the southern areas tending to be saltier than the northern sections.
In summary, while the Caspian Sea contains salt, it is more accurate to classify it as brackish rather than fully “saltwater” like the Earth’s oceans.
Is that where beluga caviar comes from?
Yes. Historically, the Caspian Sea has been the most famous source for beluga caviar.
Beluga sturgeon (Huso huso)—the fish whose roe is used to produce this prized caviar—are native to the Caspian Sea and, to a lesser extent, the Black Sea basin. For centuries, countries around the Caspian, notably Russia and Iran, dominated the global beluga caviar trade.
Because beluga sturgeon are slow to mature and have been heavily overfished, their populations have declined, leading to strict regulations and conservation efforts. While other regions now attempt to farm or produce beluga caviar, the Caspian Sea remains historically synonymous with this luxury delicacy.
What is the Largest Freshwater Lake or Sea?
This depends on how you define “largest.” Freshwater lakes are commonly measured either by surface area or by volume:
- By Surface Area:
Lake Superior, one of North America’s Great Lakes, is widely recognized as the world’s largest freshwater lake by surface area. It covers approximately 82,100 square kilometers (31,700 square miles). - By Volume:
Lake Baikal in Russia holds the title for the largest freshwater lake by volume. Containing about 20% of the world’s unfrozen freshwater, it has a volume of roughly 23,000 cubic kilometers (5,500 cubic miles). It’s also the world’s deepest freshwater lake, reaching depths of about 1,642 meters (5,387 feet).
While the Caspian Sea is the largest enclosed inland body of water, it is not classified as purely freshwater (its water is brackish), so it does not qualify as the largest freshwater “sea.” Thus, depending on the metric used, Lake Superior (by area) and Lake Baikal (by volume) are considered the largest freshwater lakes.