We show that the ice structures determine the fate of methane during the early melt season and that sea ice may act as a sink of methane when methane oxidation occurs in specific layers of thick and complex sea ice. In spring, when ice melt starts, sea ice methane released into the ocean is the favored pathway. We suggest that changes in ice cover are thus likely to change the methane pathways in the Arctic Ocean and sea ice as a potential source of methane supersaturation in surface waters.