Abstract: A submerged small angle field-of-view optical radiometer which can passively measure ocean surface wave heights, characteristics, and statistics remotely. The mechanism involves measurement of a varying underwater radiant light field and correlation of that light field to surface wave heights. The device comprises a passive optical detector, a narrow band optical filter, a small angle field-of-view limiter and associated electronics for power, monitoring and control. The device is housed in a watertight container with an optically transmissive window and is connected to onshore or inboard electronics by a single cable. The cable carries power, monitoring, control and data signals to and from the sensor to the onshore or inboard electronics. The sensor can be bottom mounted on the sea floor or can be mounted on a submerged platform such as a submarine.