AbstractThis work is based on a study of the relative hypsographic curves of 48 lakes. The five largest belong to the Great Lakes System, the rest of the lakes are Swedish. A method for determining a mean lake form as well as statistically defined deviations from this mean is introduced. A classification system for lakes based on the lake form is discussed. A method for determining the error in lake volume calculations is presented and formulas to correct for the volume error are derived. A first outline of a model for optimization of lake hypsographic surveys is discussed.