Question

which is the worlds biggest lake

Answer 1

The salty Caspian Sea has the greatest surface area of any lake at 143,200 square miles (370,886 square kilometers). Lake Superior, on the United States/Canada border is the named freshwater lake with the greatest surface area at 31,700 square miles (82,103 square kilometers).

Answer 2

Caspian Sea is the largest lake in the world followed by lake superior and lake Victoria. 
largest fresh water lake is lake superior.