A hard chamber, also known as a hyperbaric chamber, is a sealed chamber used in medical and diving applications to simulate increased atmospheric pressure. Typically constructed of metal and equipped with pressure-resistant doors and windows, a hard chamber allows individuals to undergo hyperbaric oxygen therapy (HBOT) or decompression treatment in a controlled environment.

In medical settings, hard chambers are employed to administer HBOT, a therapy that involves breathing pure oxygen in a pressurized chamber. HBOT is utilized to treat various medical conditions such as decompression sickness, carbon monoxide poisoning, non-healing wounds, and certain infections.

In diving contexts, hard chambers are essential for decompression treatments for divers who have ascended too quickly from deep dives, leading to decompression sickness, also known as "the bends." These chambers allow divers to gradually return to normal atmospheric pressure, facilitating the elimination of excess nitrogen from their bodies.

Overall, hard chambers play a crucial role in both medical and diving fields, providing a safe and controlled environment for individuals to undergo treatments and recover from conditions associated with changes in pressure.