Investigating the optical properties of sea ice is an important key to accurately understand the energy transfer across the atmosphere-ice-ocean boundary. Recent changes in the physical properties of the Antarctic and, more notably the Arctic sea ice cover, have resulted in increased light transmittance of the ice pack with important consequences for the physical and biological systems (Meier et al., 2014;Nicolaus et al., 2012). A large number of studies have investigated the optical properties of sea ice, but most studies focused on undeformed, level and relatively more homogeneous sea ice. While some studies include deformation features such as pressure ridges (Katlein et al., 2019;Massicotte et al., 2019), there has been no dedicated investigation of the light field within and underneath these features, besides their general effect of significantly lowering light transmittance.Sea ice pressure ridges form during periods of ice convergence, when two slabs of sea ice collide, shear, and break up into blocks that pile up above and below the water line (Davis & Wadhams, 1995;Timco & Burden, 1997). The portion above the water line is called the ridge sail and is important for snow accumulation and atmospheric turbulence. The four to five times thicker portion underneath the water line is called the ridge keel (Timco & Burden, 1997), which determines the hydrodynamic interaction between ice and ocean (Castellani et al., 2014(Castellani et al., , 2015, and provides shelter to ice associated flora and fauna (Gradinger et al., 2010;Hop et al., 2000;Horner et al., 1992). Newly formed young ridges are a loose pile of individual ice blocks, characterized by significant macro-pore spaces in between the blocks (Strub-Klein & Sudom, 2012). This