Measurements of light transfer through drift ice and landfast ice in the northern Baltic Sea

•We confirm that snow is the key factor influencing the light transfer through ice.•Transmittance through bare ice is lower for fast ice than for drift ice.•CDOM and water in sea ice determine the absorption in the blue and in the red.•Maximum transmittance for ice with snow is 569–582 nm and for bare ice 548–585 nm.