Many homes in Finland come equipped with their own sauna, and at Christmas time this cosy spot becomes a sacred space associated with long dead ancestors. On Christmas Eve, it's customary to strip naked and take a long and respectful stint in the sauna, which is also believed to be home to the legendary sauna 'elf'. After the sauna session, Finns head out to the evening celebrations - while spirits of those ancestors take their place in the bubbling water.