Because of their ability to remotely measure current velocity in the water column over a vertical range from a few meters to hundreds of meters, acoustic Doppler current profiles have become increasingly important constituents of physical oceanographic research since their development in the mid-1980s. Developed from the Doppler speed log that estimated ship speed at the surface relative to speed over the ocean bottom, the ADCP was engineered to measure current speed and direction at multiple depths throughout the water column.