Aside from your sense of adventure, all you really need are gloves, a hat, and warm clothing. The three-layer technique of dressing is suggested (inner, middle and outer layer) for optimum heat retention. Don’t use cotton undergarments, as cotton holds sweat which will make you feel colder. Extra gloves, socks, hat and undergarments are suggested, in case your first pair gets wet (wet and damp clothes are not your friends when you’re staying at an ice hotel). You will also want to bring a swimsuit and sandals.
An inner court of the Hotel de Glace contains a Nordic area with a hot water spa and a sauna, and it is highly recommended you use these facilities to raise your body temperature before bedtime. Although it might seem counter-intuitive, you don’t want to keep all of your layers on while sleeping–keep on only the underlayers–again, so you don’t sweat and feel colder.
Everything in the hotel is made from blocks of ice, including the base of the beds, but a layer of wood between that and the fur-covered thermal-insulated mattress helps cut the chill. A sleeping bag with a liner and a pillow will be delivered to your room at bedtime. Although Québec gets chilly in the winter with temperatures ranging from -25 to -5 Celsius, the hotel maintains a temperature between -3 to -5 thanks to the insulation of the snow/ice (now you see why igloos were popular in the far north). The sleeping bags have a -15 to -30 rating, so you will be well protected.