Delft3D-FM model was implemented to analyze the hydrodynamics of the Mojuim and Mocajuba estuaries, the Pará River mouth, and part of the Atlantic Ocean. The model domain extended \~150 km along the coast and up to 140 km inland, incorporating wind, tides, river discharges, and bathymetry. Data from the Costa Norte Project (2017) and the Amazon Coastal Observatory (OCA) supported the simulations, which were validated against in situ tide and discharge measurements. Calibration, carried out at four tidal stations and two discharge points, showed excellent performance. Tidal adjustment presented RMSE < 10%, strong positive correlation (r > 0.9), and satisfactory efficiency (NSE > 0.85), ensuring over 90% model confidence. For river discharge, although RMSE exceeded 15%, Pearson (> 0.9) and NSE (> 0.60) indices confirmed consistent behavior between observed and simulated data. The results revealed macrotidal influence up to 50 km inside the estuaries, with amplitudes ranging from 6 m at the mouth to 4.5 m upstream. The system showed positive asymmetry, with flood lasting ~5 h and ebb ~7 h. Pará River transport exhibited bidirectional flow on the Amazon Continental Shelf, ranging from –400,000 m³·s⁻¹ (flood) to 600,000 m³·s⁻¹ (ebb), with the river plume propagating eastward along the Eastern Amazon coast, corroborating previous observations. In the Mojuim and Mocajuba estuaries, positive discharge (~63 m³·s⁻¹) predominated, consistent with historical records and indicating stable outflow during ebb. These results highlight the strong interaction between tides and river discharge in the Amazon estuary, emphasizing asymmetry processes, bidirectional flow, and eastward propagation of the river plume along the eastern coast. The study advances the understanding of Amazon coastal dynamics and reinforces numerical modeling as a strategic tool for environmental monitoring and management of riverine and estuarine systems.