Introduction Arctic sea ice has declined and become thinner and more seasonal during the last decade. One consequence of this is that the surface energy budget of the Arctic Ocean is changing. Solar light transmitting into and through sea ice is of critical importance for the state of sea-ice and the timing and amount of primary production. The light field in and under sea ice is highly variable: horizontally, vertically, and over seasons. At the same time, observations of light transmittance through sea ice are still sparse, because the under-ice environment is difficult to access and high quality measurements are challenging. Furthermore, it is necessary to generalize measurements in order to obtain Arctic-wide estimates of light conditions and energy budgets.