Wind turbines in offshore wind farms operate in an extremely harsh environment. Besides the buffeting of constant waves and often exceedingly strong winds, they have to withstand the corrosive effects of salt water. Due to the way the turbines are constructed and their location, it is inevitable that some seawater will enter the turbine tower. The water level inside the tower must be continuously monitored in order to detect any leaks at an early stage that can cause corrosion. To determine the mechanical loads and the generating capability of a wind power array, the tidal and wave height measurements on the outside are also required.