| Land |
| Singlebeam - 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 |
| Isolated sounding - depth value that is not part of a regular survey or trackline |
| 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 |
| Interpolated based on a computer algorithm - depth value is an interpolated value based on a computer algorithm (e.g. Generic Mapping Tools) |
| Digital bathymetric contours from charts - depth value taken from a bathymetric contour data set |
| Digital bathymetric contours from ENCs - depth value taken from bathymetric contours from an Electronic Navigation Chart (ENC) |
| Bathymetric sounding - depth value at this location is constrained by bathymetric sounding(s) within a gridded data set where interpolation between sounding points is guided by satellite-derived gravity data |
| Predicted based on helicopter/flight-derived gravity data |
| Depth estimated by calculating the draft of a grounded iceberg using satellite-derived freeboard measurement. |
| 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. |
| Unknown source - depth value from an unknown source |
| Steering points - depth value used to constrain the grid in areas of poor data coverage |