The study covers part of a project aiming at the investigation of cell failures and assessment of service life of a cellular cofferdam breakwater which was built as a permanent structure at Calumet Harbor in Lake Michigan near Chicago, Illinois. The structure was analyzed for a series of direction-dependent local wave load patterns using two-dimensional vertical slice and three dimensional finite element models in parallel to evaluate the performances on a comparative basis. A system of strain gauges designed to obtain data to be used as reference for validation of the finite element models was installed in two of the cells of breakwater. The analyses results showed that predictions by both models regarding the interlock forces, displacements and lateral pressures were consistent in the construction simulation stage. Differences, however, became more predominant as the permanent effects of wave loads were simulated. Regarding the wave load analyses, three-dimensional model predictions resulted in a better agreement with the field recorded data.