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The technical and commercial feasibility of developing a miniature dual wavelength optical beam attenuation meter for use with Automated Underwater Vehicle (AUV) systems such as the REMUS is evaluated. The meter will use a novel Scattering overDual-Pathlengths (SDP) approach, where two measurements of light backscattering are made with identical angular weighting functions but over different pathlengths. Using a single source, beam attenuation is readily derived from the ratio of scatteredfluxes measured by the detectors and the difference between the two pathlengths. A key issue to address in determining feasibility is the tradeoff between increasing resolution and decreasing signal return as a result of increasing pathlength differentialsbetween the two scattering measurements. A second challenge will be determining how to minimize and account for any light that is scattered more than the single incident in the sample volume (intersection of detector field of view and source beam), butstill makes it to the detector. The SDP approach is likely the key to solving the apparent paradox of making high resolution attenuation measurements over very long pathlengths with a compact sensor. The sensor will be low power, robust, and have theapproximate dimensions and volume of a hockey puck.Beam attenuation is a key property in diver visibility and vulnerability models, lidar performance models, and in determining particle concentrations in natural waters. Currently there is no commerciallyavailable miniature sensor for measuring optical beam attenuation with high accuracy. Such sensors are needed for deployment on the new generation of sampling platforms such as AUVs, profiling/gliding floats (e.g., the ALACE floats), and long-term,unattended observing systems. In the near future, thousands of such sampling platforms will be built. Revenues for a compact, high accuracy attenuation sensor costing about $3000 per unit are expected to be about $1.5 million annually (500 units per year).