The phrase "largest of greatest lake" is a bit ambiguous. It seems to be asking for the largest lake that is also considered one of the "greatest" lakes. However, "greatest" is subjective and can be defined based on various criteria like size, depth, beauty, historical significance, etc.

Here are some possibilities depending on what "greatest" means:

* Largest by surface area: Caspian Sea is the largest lake in the world by surface area. However, it's often categorized as an inland sea due to its salinity and size.

* Largest by volume: Lake Baikal in Siberia holds the most water and is considered the deepest lake in the world. It's often recognized as one of the most unique and ecologically important lakes.

* Largest by other factors: Other "greatest" lakes could include the Great Lakes of North America, known for their economic and cultural significance, or Lake Victoria in Africa, known for its biodiversity and role in the region.

To give a more precise answer, you need to clarify what "greatest" means in this context.