This work provides an improved medium resolution (~ 250 m) global land/water mask derived from an earlier data set (https://doi.org/10.17632/9r93m9s7cw.1), and includes the recent changes in the environment, as well as fixes some artifacts in the earlier data set. It highlights the use of global medium resolution clear sky true and false color imagery to detect changes in global surface water coverage, and helps to improve satellite water color retrievals in many new and recent water bodies.