It's not just a plain sauna either. It was designed by Finnish celebrity hairdresser/model/designer/singer Teuvo Loman and recently placed third in a global food service new concepts competition.
The 15-person area that includes the sauna sports a Burger King-branded motif and also includes a laundry room, dressing room, showers, and a media lounge. The sauna itself is meant to accommodate 10 people and comes with a 48-inch TV. The media lounge also comes with a TV (55-inches), audio system, and Playstation 4. You can also place food orders on site rather than having to go over to the restaurant area.
Photos via Restel.