This image dataset provides histological micrographs of Antarctic deep-water sponges (Demospongiae and Hexactinellida) collected for study of microbial symbionts and histology during expedition JR17003a (RRS James Clark Ross, 2018) in Prince Gustav Channel, western Weddell Sea. Histological sections of 7-30 µm were stained in Masson's trichrome and images were captured on a Zeiss Axioskop 2 plus with a QiCam camera using Northern Eclipse software. Image files are labeled with expedition, station, sample ID, and magnification. Masson's trichrome highlights collagen in blue (especially spongin).Three images of a calibration scale at 10x, 20x, and 40x magnification are included (see Further details link). To derive the scale for an image, open both the image and the corresponding calibration scale of the same magnification in e.g. ImageJ or Photoshop and draw a line across the calibration. Then pull that line over to the image as a layer. Each smallest mark equals 10 micrometers.