The use of high-power laser radiation in water is not common. A major reason for this is the high absorption in water above 550 nm and the resulting higher requirement for laser power. Due to the progressive developments in laser technology in the range of blue radiation with more powerful laser sources, new areas of application with high power requirements can be developed. An application for water treatment using laser radiation is unknown but has a high potential due to the high energy density that can be generated by laser radiation. In this work, seawater from the North Sea was disinfected using laser radiation. A laser with wavelengths of 448 nm and a power of 1400 W was used. The water was irradiated statically in a cuvette (water volume of 20.67 ml).