The explanation of why we can't breathe underwater and how a regulator helps scuba divers. The hosts reveal the dangers of ""the bends"" where nitrogen builds up in the blood, the treatment, and the prevention. The regulation, structure, and function of living systems are also presented. Organisms and their environment, calculation of variables such as temperature, pressure, density, and elevation/depth, and the hosts also explain about the effects of differences in density and energy transfer on the activities of and in the ocean.