The largest unit of volume is the cubic kilometer (km³). It is used to measure extremely large volumes, such as the volume of oceans or large lakes. One cubic kilometer is equal to 1,000,000,000 cubic meters (m³).
To put it into perspective, the volume of the Earth’s oceans is estimated to be around 1.332 billion cubic kilometers. This unit helps in understanding and comparing vast volumes in a more manageable way.