Optical studies of the suspended load in the Gulf of Maine have been performed in conjunction with hydrographic and biological analyses between late winter and early fall. Major particle sources are coastal runoff, benthic resuspension, and biological activity. Analysis of the optical efficiencies of the particles suggests that runoff and resuspension sources are restricted to the nearshore and shallow regions. The variabilities in the coupling and discoupling of the optical and hydrographic features of the Gulf demonstrate that advection is primarily responsible for the distribution of clear water masses, while settling, vertical mixing, and productivity are the processes behind the distribution of particles.