Accurate mapping of the basement is one of the most crucial factors to the construction of harbour facilities and bridges in the coastal areas. In shallow waters, the seismic reflection method employing acoustic profiling technology often fails to image the basement geometry beneath the sediment cover in many cases. We present the result of a shallow marine seismic refraction survey using two ships, 12-channel hydrophone arrays deployed on the bottom and a borehole sparker or percussion powder as sources. Velocity structure was computed by tomography since data from more than 6 different source points had been collected for one spread. A comparison of the results of the refraction survey with drilling logs demonstrates remarkable consistency in basement ge-ometry. It thus appears that the refraction method in this study is an efficient and cost-effective way to investigate the basement structure in coastal area, river, and lake.