A striking ocean warming is documented in one of the main basins of the interior Arctic Ocean (the Canada Basin). The upper ocean in the Canada Basin has seen a two-fold increase in heat content over the past three decades. The warm waters responsible for this buildup of ocean heat originate hundreds of kilometers to the south of the interior Canada Basin. These waters are formed at the geographic margins of the basin, where reduced sea-ice extents in recent years leave the surface ocean more exposed to summertime solar warming. Arctic winds drive these exceptionally warm waters into the interior Arctic Ocean, below the surface water layers, effectively archiving the heat. This means the effects of sea ice loss are not limited to the ice-free regions themselves, but lead to increased heat accumulation in the interior of the Arctic Ocean that can have climate effects well beyond the summer season.