Hyperbaric oxygen therapy (HBOT) is a wonderful fusion of ideal gas laws and modern medicine. As we are slowly beginning to evolve our understandings about ventilation and perfusion models, we are getting to know more about the benefits of the so-called dissolving oxygen in plasma under increased pressures. We have come a long way in understanding the physics of HBOT from using huge chambers that were used to pressurize oxygen; the first such model could be traced back to the 1600s. Our centuries of experience with HBOT helped us to form a basic theory that when a patient is given 100% oxygen under increased pressure, there still remains room for dissolving more oxygen in plasma. When pressures are increased, we can achieve a saturation of plasma as well, which forms the backbone of the utility of HBOT in modern medicine. Mostly oxygen is carried in our body by binding with hemoglobin, which can be maximally saturated up to 97%. However, physiologically, some amount of oxygen is said to be transported as dissolved oxygen; it is this dissolved oxygen that is increased when delivered under increased pressures. HBOT now stands as a treatment modality for various disorders not only limited to respiratory system but also connective tissue disorders, wound healing, eye and ear disorders, and various other refractory conditions. HBOT is gaining special attention after the COVID-19 pandemic, where it has shown some promising results. HBOT still remains a versatile topic of research and shows potential for further improvement.