The ECHO awaits deployment aboard the R/V Lake Guardian. It utilizes sound to image objects, as well as geologic features, on the lake floor. The black rectangular strip on the lower half of the vehicle is one of the transducers, the instruments that emit and receive sound waves that bounce off the bottom. The cylindrical instrument on the top and front of ECHO communicates with a beacon mounted on the ship; they work together to measure the distance of the vehicle from the ship. Image courtesy of Thunder Bay 2001, NOAA-OER.