Sea temperature and sea currents are very useful ocean parameters in human activities such as marine-based economic activities, transportation, and scientific research. Sea temperature and sea currents data in Indonesia usually obtained from satellites and forecast model called Ocean Forecasting System (OFS BMKG) because not all Marine Meteorological Station in Indonesia equipped with sea temperature and sea currents observation instruments to perform the measurements directly. One solution to overcome these problems is to design a portable sea temperature and sea currents measuring device that easily operate and concise. The design of the portable sea temperature and sea currents measuring device in this study utilizes easily designed electronic components and can display real-time data of sea temperature and sea currents automatically. The components used in this research are DS18B20 sensor, YFS-201 sensor, HMC5883L sensor, and the Arduino Nano 3.0 microcontroller for data collection and processing. Once processed in the microcontroller, data is then displayed with a Visual Studio 2015-based application. The result of this study is the device can operate within correction range allowed by WMO and BMKG, and OFS model verification test show that the instruments can works properly with average temperature correction of 0.17525 C, sea current direction with correction of 4.85 degrees, and sea current speed has the correlation of measurement about 0.94.