Earthquake poses significant threat to offshore and marine structure. Many earthquakes in past have shown that local site conditions significantly affect the intensity of earthquake and so to the damages caused by those earthquakes. This study involves the seismic site characterization and ground response analysis of an offshore site in Western Yemen, based on extensive field test results and results of large number of laboratory tests on undisturbed samples. Large number of seismic cone penetration tests (SCPT) were conducted as field test analysis for site characterization and evaluation of low strain soil stiffness. Dynamic properties such as shear modulus and damping ratio of soil samples corresponding to very low to high strain level were established based on laboratory tests. Peak ground acceleration (PGA) was evaluated using the generated synthetic ground motion. This study also gives a site specific design response spectrum based on Eurocode, corresponding to 475 and 2500 year return period.