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.
Depending upon the clarity of the water LiDAR can measure depths from 0.9m to 40m with a vertical accuracy of 15 cm and horizontal accuracy of 2.5m. Both pulses are analyzed to establish the depths of the water and the elevations of the shoreline. Bathymetric information is very important near coastlines, in ports and near beaches and banks, it is also used to locate objects on the ocean floor.