This is a short summary of a published work on Synthetic Aperture Radar (SAR)-based land masking for ship detection after applying little modification in the original process [1]. The land masking in SAR images is commonly done by using either archived shoreline databases or an image segmentation which cannot appropriately masks all of the very small islets and exposed sea rocks in the coastal regions of Korean Peninsula. Therefore, in previous work coastline maps from Electronic Navigational Chart (ENC) were just used to retain the land objects from all extracted objects of KOMPSAT-5 images. In this study the method [1] is further improved by applying the ENC-based topography data at various depths which can also mask small sea rocks submerged just beneath the sea surface. Thus, this improved method of land masking could be useful for precise ship detection in SAR images, especially for the geographically complicated coastal regions with many small islets, exposed and submerged sea rocks like Korean Peninsula.