A wave measurement buoy is a spherical, floating hollow body used to collect sea state parameters. The buoy is anchored to the sea floor with a bungee cord and moves along with the sea surface. Vertical acceleration is measured within the buoy and converted to vertical deflection. The data are then transmitted by radio to a computer and can subsequently be viewed on the COSYNA Internet portal. Among its various uses, the wave measurement buoy data are also necessary for improving sea state models.