| Land |
| Single beam - depth value collected by a single beam echo-sounder |
| Multibeam - depth value collected by a multibeam echo-sounder |
| Seismic - depth value collected by seismic methods |
| ENC sounding - depth value extracted from an Electronic Navigation Chart (ENC) |
| Lidar - depth derived from a bathymetric lidar sensor |
| Depth measured by optical light sensor |
| Combination of direct measurement methods |
| Predicted based on satellite-derived gravity data - depth value is an interpolated value guided by satellite-derived gravity data |
| Depth value at this location is based on bathymetric depths from multiple sources including measured and derived data and included within a gridded data set where interpolation between sounding points is guided by satellite-derived gravity data |
| Pre-generated grid - depth value is taken from a pre-generated grid that is based on mixed source data types, e.g. single beam, multibeam, interpolation etc. |
