This chapter describes how modeling contributed to understanding the resonance and tides of the Bay of Fundy and Gulf of Maine, and through that understanding, provided a fundamental tool to other studies. It outlines the effects of tidal power barriers and provides the ties to biological and geological studies. The chapter explores how the area has been a test bed for developing techniques in three-dimensional modeling. Modeling's coming of age is typified by the work done studying the Bay of Fundy and Gulf of Maine. Numerical modeling studies have contributed to the understanding of aspects of the oceanography of the Bay of Fundy and Gulf of Maine. The formulation developed by L. P. Roed and C. K. Cooper, in which the compatibility equations are integrated along the characteristics, is useful because the dynamics specified along the boundary are at least consistent with the dynamics in the interior of the model.