CDEX (Center for Deep Earth eXploration) as an implement organization of IODP (International Ocean Discovery Program) leads to site survey measurements prior to drilling operation for the purpose of safety evaluation. Ocean current monitoring is one of observations by use of two mooring systems. The top buoy equipped with a long ranger multi-current ADCP (Acoustic Doppler Current Profiler) is designed towing vertically at 300-500m below the sea level. Other equipment as a single current ADCP, CTD (Conductivity Temperature Depth profiler), acoustic separator kit and a sinker bar are aligned vertically at further below. The long-term current direction, velocity and vertical profile are available.