Airborne LIDAR can also be used to create bathymetric models in shallow water. Bathymetric systems such as the Optech Aquarius utilize a green spectrum (532 nm) laser beam to penetrate the water. The beam penetrates the water and also detects the bottom surface of the water under favorable conditions. The data acquisition technique involves a sea floor mapping component and a ground truth component that includes video transects and sampling. The data obtained shows the full extent of the land surface exposed above the sea floor. The mapping yields onshore topography as well as underwater elevations.