Boaters rely on NOAA’s nautical charts for depth measurements so they don’t accidently ground on sandbars or other underwater obstructions. NOAA gets these measurements by using hydrographic survey technology from onboard ships and smaller boats. Sometimes, though, the water may be too shallow for safe operation of the survey vessels. Lidar systems systems can be used in some cases, but that technology doesn’t work well in murky water.
Original article: Using Robots to Map Shallow Water on Nautical Charts