What is the largest lake by volume of water?

The largest lake by volume of water is the Caspian Sea, containing roughly 78,200 cubic kilometres of water. Despite its name, it is a landlocked body of water with no natural connection to the world’s oceans, so geographic references commonly classify it as the world’s largest lake.

The Caspian stretches between Europe and Asia and borders Russia, Kazakhstan, Turkmenistan, Iran, and Azerbaijan. Its surface lies about 28 metres below global sea level, and the basin is divided into shallow northern waters and much deeper central and southern sections. The southern basin reaches depths exceeding 1,000 metres.

Lake Baikal is the common alternative answer because it is the world’s largest freshwater lake by volume. Baikal holds about 23,600 cubic kilometres—an extraordinary amount, but less than one-third of the Caspian’s total. Lake Superior is larger than Baikal by surface area, yet far smaller by volume.

The Caspian’s “sea” label reflects its enormous size, saltiness, and history as a remnant of ancient marine basins. Its water level changes over time, so exact area and volume estimates vary, but its ranking remains clear.