Abstract: This dataset includes records of the specific growth rates measured for 46 clonal diatom strains originally isolated during the research cruise NBP-1701 across the Pacific sector of the Southern Ocean during December 2016-January 2017. Strains were grown under continuous light (130 µmol m-2 s-1) at up to 8 temperatures that span all or most of each strain’s thermal niche width, from 0-12 degrees C, which encompasses each strain’s optimum temperature for growth. Strains have been molecularly identified to species via 18S Sanger sequencing. Data include the following information for each record: Internal lab strain reference ID, date collected, latitude, longitude, Southern Ocean region, species, tested temperature, replicate number and specific growth rate. Data are provided in comma-separated values (csv) format.