The validation of numerical models for large lakes is difficult because of sparse field observations. In this study, a Froude-Rossby scaled physical model of Lake Ontario, North America, is used to support numerical simulations. Experimental data are consistent with available field observations and provide a more comprehensive view of lake-wide features that include, in the absence of wind, strong eastward flows along both northern and southern shorelines, a large cyclonic gyre in the Rochester basin, and smaller midlake cyclonic eddies. With a west wind (most common direction), a well-defined westward flow in the middle of the lake separates an anticyclonic gyre in the north from a cyclonic gyre in the south. A review of numerical models shows that most models can capture general features of these observed patterns but do not always reproduce all details, especially in nearshore regions. A numerical model based on the Environmental Fluid Dynamics Code (EFDC), with a 200-m resolution in nearshore regions, is developed.