A bathymeter is another term for a bathometer - an instrument for measuring the depth of water.
The instrument used to measure the depth of the sea is called a bathymeter or echo sounder. It sends sound waves to the ocean floor and measures the time it takes for the sound waves to bounce back, allowing for the calculation of water depth.
Gary C. Guenther has written: 'Error analysis of pulse location estimates for simulated bathymetric lidar returns' -- subject(s): Aeronautics in oceanography, Optical radar, Hydrographic surveying 'Simulations of the impact of inhomogeneous water columns on the temporal stretching of laser bathymeter pulses' -- subject(s): Deep-sea sounding, Optical radar, Lasers 'Depth estimation in the airborne oceanographic lidar postflight bathymetry processor' -- subject(s): Deep-sea sounding, Oceanography, Data processing 'Prediction and correction of propagation-induced depth measurement biasas plus signal attenuation and beam spreading for airborne laser hydrography' -- subject(s): Oceanography, Underwater light