The present invention relates to an instrument for marking and environmental monitoring in regatta courses. Incorporated by inflatable pneumatic platform and modular mast, foldable and transportable in compact packing of reduced size. It is intended to simultaneously define the area of conducting such nautical trials, at the same time as the environmental conditions thereof are characterized, in both meteorological and oceanographic terms. The system comprises an inflatable pneumatic float (1) and a support structure—mast—(2), which serves to hold the meteorological (3) and oceanographic (6) instrumentation, as well as the group of elements intended for communications (4), electromechanical components (5) and anchorage system (7). The marked modular level and reduced weight thereof, allow handling from craft of reduced cargo-carrying capacity without the help of additional infrastructures, which has a close relationship with the degree of variability in the regatta courses when competitions are under way.