Description This dataset contains 238 Olympus RAW (.ORF) images from the T0-uw underwater photogrammetric survey conducted for the MANATEE project at the Costa Paradiso (Sardinia, Italy) experimental site. Images document one of the two 5×3 tile grids with 30 stained thalli of the crustose coralline alga Lithophyllum stictiforme mounted on granite tiles with four coded photogrammetric targets each. Calibrated scale bars and a color checker were included in the scene for metric and colorimetric control. Acquisition setup Camera system: Olympus OM-D E-M1 Mark II (20 MP) with Olympus 9–18 mm lens set to 9 mm, in Olympus PT-EP14 housing with AOI glass dome port. The dome port was centerd and aligned to the entrance pupil of the camera lens using the procedures described in Menna, F., Nocerino, E., Fassi, F., & Remondino, F. (2016). Geometric and optic characterization of a hemispherical dome port for underwater photogrammetry. Sensors, 16(1), 48. The images were acquired with fixed focus, preset at the beginning of the image acquisition and then left unchanged throughout the survey. Images acquired by a SCUBA diver immediately after installation of the grids (T0-uw). About ~200 images were typically used per survey in the study; GSD better than 0.2 mm was obtained. Control elements: calibrated scale bars and a color checker imaged with the tiles. Example EXIF (from file P2078993.ORF) Dimensions 5240×3912 px; Date taken 2025-02-07 14:07; Camera Olympus E-M1 Mark II; Lens 9 mm; Exposure 1/250 s, f/5, ISO-640; Exposure program Manual; Flash mode compulsory; File size ≈ 17.4 MB. (Per-file settings vary; this is a representative sample.) What’s included /raw/ — 238 .ORF files (Olympus RAW), total ≈ 4.1 GB. Purpose & link to the paper The images support the validation of a non-destructive underwater optical metrology workflow to detect sub-millimetre differences on L. stictiforme thalli. The methodology, equipment and accuracy assessment (including sub-mm potential and reproducibility better than 0.5 mm) are described in:Nocerino, E., Menna, F., Calantropio, A., et al. (2025) “Underwater optical metrology for precision monitoring of marine habitats: the MANATEE project,” ISPRS Archives XLVIII-2/W10-2025, 207–214. Geographic coverage Costa Paradiso (Sardinia, Italy); nearshore coralligenous assemblages. Temporal coverage / Dates Data collected: 2025-02-07 (T0-uw). Methodology / Processing Images are suitable for self-calibrating bundle adjustment and dense reconstruction in Agisoft Metashape (or equivalent). The scene includes coded targets to locally rigidly register each tile across epochs and scale using the calibrated bars.