||An underwater radiometer designed for multiwavelength profiling and surface measurements of irradiance, radiance, temperature, and remote sensing reflectance in the SeaWiFS wavelength bands. The standard instrument comes with 6 (expandable to 7) channels each of downwelling irradiance and upwelling radiance, and the user can select from 9 specialised detector channels at 412, 443, 490, 510, 555, 665, 683, 780 nm and Photosynthetically Active Radiation (PAR: 400 to 700 nm). The optical sensors are based on photodetectors, each with its own narrow-band (10 nm) interference filters. The PRR-600 irradiance collector is Teflon, backed with 100% acrylic, optimized for excellent cosine response in water. The instrument is designed to be hand-lowered, and includes a temperature sensor and pressure transducer with a 200m depth range. It is powered and controlled from a deck unit and data are transmitted to the deck via a conductive cable. There is the option to include additional upwelling and downwelling sensors, tilt and roll sensors, and two analog input channels. The instrument can also be configured for moorings, free-fall deployment, and low profile for towed applications.