The variation of hydrodynamic forces and moments on different circular pile sections of 1.0 to 2.0 m diameters in the offshore Niger Delta Environment has been investigated. Available meteorological and oceanographic data were used to obtain wave characteristics. Inertia coefficient, cm and drag coefficient, cd were obtained from Reynolds number, Re, while maximum inertia force, kim, maximum drag force, kDm, maximum inertia moment, Sim and maximum drag moment, SDm were evaluated from standard charts. The revealed variation of hydrodynamic forces and moments with pile diameter showed that the horizontal forces and moments increase as pile diameter and wave height increase. Drag dominated forces and moments were obtained for wave heights greater than 3m.