Satellite estimates of chlorophyll a concentration (mg m-3) in the region near Hunga Tonga-Hunga Ha'apai used in the analyses presented in the article "Satellite detection of a massive phytoplankton bloom following the 2022 submarine eruption of the Hunga Tonga–Hunga Haʻapai volcano" (accepted for publication in Geophysical Research Letters). Data were obtained as the Globcolour products downloaded from the Copernicus Marine Service (products OCEANCOLOUR_GLO_CHL_L3_NRT_OBSERVATIONS_009_032 and OCEANCOLOUR_GLO_CHL_L3_REP_OBSERVATIONS_009_085). These data products were replaced on July 5, 2022 by updated data products (OCEANCOLOUR_GLO_BGC_L3_NRT_009_101 and OCEANCOLOUR_GLO_BGC_L3_MY_009_103 on https://marine.copernicus.eu/). Files whose names start with 'Chlorophyll_a_map_' are maps of chlorophyll a concentration for the day indicated in the filename and in the file header. In those files, first columns is latitude (°N) and first row is longitude (°E). NaN depicts missing observations. The file named 'Chlorophyll_a_timeseries.csv' is the time-series in the coordinate box between 20.3–20.9°S and 174.8–175.9°W depicted in Figure 2 of the manuscript. Columns are date, average concentration, and the 5th and 95th percentile of the concentration. NaN depicts missing observations.