The dataset provide the records of benthic diatoms attached on the diatom boards which were set on the artificial floating islands (AFIs) established on seawater in Anping Historical Waterview Park in Tainan, Taiwan. Diatoms were cultured with diatom boards and sampled four times from October to December of 2017. A total of 45 diatom species belonging to 22 genera were identified. Among them, the Navicula genus has the largest richness, and Achnanthes subsessilis and Nitzschia longissima were the dominant species in number.