A seasonal Secchi depth atlas has been developed for the world's coastlines. Optical data have been compiled from the National Oceanographic Data Center and open literature for water depths less than 500 meters. These data have been averaged by one-degree squares and sorted by season and placed in a category of 6 classes of Secchi depth ranges. Four charts were used to cover the world at a scale of 1:12,233,000, and four seasons were selected to encompass 3-month intervals. Additionally, annual mean Secchi depths have been compiled in 4 charts. Secchi depth data were found for approximately 50% of the world's coastlines. In the areas where no optical data were available other oceanographic, meteorologic and geomorphic data sources were used to estimate the expected Secchi depth ranges. Secchi depth values show high temporal and spacial variability in certain coastal regions, even though the amount of data was highly limited. This variability suggests that improved techniques of compiling coastal optical properties, such as through use of satellites be examined both to aid in understanding historical ship data, and to obtain additional optical data.