Abstract An instrument has been developed that measures finescale velocity and vorticity in seawater based on the principles of motional induction. This instrument, the electromagnetic vorticity meter (EMVM), measures components of the gradient and Laplacian of the electrostatic potential field induced by the motion of seawater through an applied magnetic field. The principal innovation described here is the development of a sensor for measuring small-scale vorticity. The sensor head consists of a strong NdFeB magnet, a five-electrode array, low-noise preamplifiers, and 20-Hz digitizers. The main electronics includes attitude sensors, batteries, a microprocessor, and a hard disk. The vorticity sensors are usually carried on a heavy towed vehicle capable of vertically profiling to 200 m and at tow speeds of several knots. The theoretical response functions of the EMVM are evaluated for velocity and vorticity. Extensive measurements were obtained in Pickering Passage, Washington, as the sensor vertically pr...