Optical communication in the atmosphere, space, the marine boundary layer, and underwater is being investigated for a variety of applications. Three classes of optical communications systems will be addressed: OCULT (Optical Communications Using Laser Transceivers), ELOS (Extended Line-of-Sight) optical communications, and satellite-to-subsurface optical communica-tions. OCULT is a 10.6 bt, high rate reciprocal tracking heterodyne laser com-munications system designed for nearly all-weather duplex video bandwidth communications to horizon limited ranges. Of special interest are effects of coherent propagation through turbulent and turbid atmospheres. The ELOS system is a 1.06 µ optical aerosol scatter communications system for ranges of 30 to 300 miles. Scattering measurement at 40 to 80 miles through the marine boundary layer will be presented. The satellite-to-subsurface communication efforts deal with blue/green transmission from a satellite, through the atmo-sphere (including clouds) to a submerged receiver, exploiting the blue/green "window" in ocean water. The multiple forward scattered and diffusion trans-port of semiplane waves through clouds and ocean waters will be discussed.