Opened in 2016 and adjacent to the Icehotel site by the river, the big plus here is that it's open year-round. Even in summer, guests have an 'ice experience' with frigid, themed rooms full of ice sculptures, and an ice bar. Insulated to keep the cold in during summer, Icehotel 365 forms part of the original Icehotel in winter.
Note that only suite-category rooms have en-suite bathroom.