Micronesia covers 7,4 million km2 with some 2,100 islands and atolls. In the early 20th century, naturalists had collected algae and seagrasses from only a few islands and atolls across this vast region. In the 1960s, Roy Tsuda —graduate student—set out to change that. Over the following decades he published >60 papers on the marine macrophytes of Micronesia and another 30 covering parts of Polynesia and the central Pacific, southern Japan/Ryukyus, the Philippines and elsewhere. Some 185 genera and 653 species of benthic marine algae and seagrasses were recognized for Micronesia, including about 60 new species. By the end of his life he added another 30 publications detailing biogeographic distributions throughout Micronesia and parts of northern Polynesia.