Instrumentation with the drifter principle of the Lagrangian method is used to detect the movement of ocean currents combined with measurement of oceanographic parameters. RHEA can be used to monitor the condition of corals in the water, marine observation data to monitor climate change, validation and improvement of physical models, etc. RHEA is equipped with sensors for turbidity, pH, temperature, DO (dissolved oxygen), conductivity, humidity, and pressure. Each movement will be accompanied by the coordinates of the RHEA position. The communication system is available using the iridium satellite (worldwide) and also Radio Wireless Telemetry (local). RHEA has ability to adjust the range and display mode of the sonar.