In the present paper simulation of tidal currents on three-dimensional geometry of the Persian Gulf is performed by the solution of the depth averaged hydrodynamics equations. The numerical solution was applied on two types of discritized simulation domain (Persian Gulf); with and without major islands. The hydrodynamic model utilized in this work is formed by equations of continuity and motion in two-dimensional horizontal plane. The effects evaporation and rainfall are considered in the source term of the continuity equation. The effects of bed slopes in x and y directions are considered in the partial differential terms representing the variation of hydrostatic pressure and the effects of bed friction, as well as the Coriolis effects are considered in algebraic terms of two equations of motion. The unstructured finite volume method is applied for solving the governing equations on overlapping control volumes formed by triangular cells. Using unstructured triangular meshes provides modeling of the geometrically complex flow domains, such as the Persian Gulf region. The results of the developed model for fluctuating flow on the variable bed elevation are compared with an available analytical solution of flow in a quadrant variable bed slope and Parshall flume. The accuracy of the finite volume flow solver is assessed by comparison between numerical results and the analytical solution and experimental measurements reported in the literature. The performance of the computer model to simulate tidal flow in the Persian Gulf domain is examined by imposing tidal fluctuations to the main flow boundary during a limited period of time and comparison of the computed results in an arbitrary location with available data from admiralty tide tables. Finally, a comparison was made between the model results of the two types of discritized simulation domain.