Where is the sauna in osmosis Jones?

In "Osmosis Jones," the sauna is depicted as a location within the human body, specifically in the area representing a part of Frank's body where the immune response occurs. It serves as a metaphorical space where the characters, including Osmosis Jones, interact and strategize against the virus threatening Frank's health. The sauna is portrayed as a hot, steamy environment, emphasizing the body's efforts to fight off illness.