This dataset contains reflectance measurements of ponds and ice surfaces acquired during RV POLARSTERN cruise PS106 with two Ocean Optics STS-VIS spectrometers.The Ocean Optics setup has been built and designed at German Aerospace Center (DLR) Oberpfaffenhofen by Thomas Schwarzmaier, Stefan Plattner and Peter Gege and consists of one upward-looking sensor equipped with a cosine collector and one downward-looking sensor equipped with a 1 degree fore optic.Measurements were referenced with a spectralon panel. The data from the upward-looking spectrometer was used to correct for illumination changes.The bare ice data has been acquired under diffuse illumination conditions. The melt pond data has been acquired under clear sky conditions.Each folder contains three subfolders:1) photos: field photographs of each target taken with a downward-looking action cam attached to the spectrometers.2) raw: raw measurements of dark current, reference (spectralon panel) and target (bare ice surfaces) for both spectrometers.3) reflectance: reflectance data computed from the raw measurements (associated raw files are documented in each reflectance file). The .RE files contain information on irradiance change, the .RL files contain the reflectance spectra that were not corrected for irradiance change and the .R files contain the reflectance spectra that were corrected for irradiance change.