The Indonesia Continental Shelf (LKI) expedition was held during September - October 2020. During the survey, there were ten Conductivity Temperature Depth (CTD) measurement stations that located extending from the west of Mentawai Island to the Indian Ocean. In this study, two-line of subsurface temperature, salinity, and density data were plotted longitudinally. The results show the unique feature between the open ocean and coastal area, the characteristic from open ocean did not affect the characteristic in coastal zone, it is shown from the salinity data. The maximum salinity found in the thermocline layer, between 100-150 m in both of line. The salinity increases from the surface until the thermocline, then slightly decreases to the deep layer. The surface salinity in the coastal area significantly different from the open ocean, it is less than 34 PSU. That is the fact that Wyrtki Jet current did not induce the open ocean water to the coastal water in the subsurface. Otherwise, the temperature and density have a similar pattern with range values around 9-31°C.