Phillipp Müller (16), Fabian Haas (16) and Niklas Nathmann (17) from Trittau and the surrounding area want to make a smart contribution to effective coastal protection. Measuring buoys are generally used in coastal regions and at sea to track the development of waves and react to conspicuous changes. The young researchers have developed a measuring buoy that they have equipped with a standard smartphone. They stowed the device, which detects its own movement thanks to an integrated acceleration sensor, inside the buoy. They also programmed the necessary apps to transmit the measured values to a central computer. If there is no radio connection at the buoy's location on the high seas, the device collects the data in its own memory. The cell phone buoy has already passed its first practical test - in the local wave pool.