Ocean vs. Lake: Size Comparison

An ocean is vastly larger than any lake. By definition:

• Oceans are the five principal divisions of the World Ocean (Pacific, Atlantic, Indian, Southern, Arctic), covering ~71% of Earth's surface (361M km²). The smallest, the Arctic Ocean (14M km²), still dwarfs the largest lake.
• Lakes are inland bodies of fresh or saline water, surrounded by land. The largest by surface area is the Caspian Sea (371,000 km²)—often called a sea due to size and salinity, but hydrologically a lake. The largest freshwater lake is Lake Superior (82,100 km²).

Comparison: Arctic Ocean (14M km²) > Caspian Sea (0.37M km²) > Lake Superior (0.08M km²). The Arctic Ocean is ~38× larger than the Caspian Sea and ~170× larger than Lake Superior.

Key distinctions: Oceans are saline, connected, tidally influenced, and have oceanic crust. Lakes are isolated, can be fresh/saline, no tides (seiches only), and sit on continental crust.