Why does a temperature that feels comfortable in air quickly become uncomfortable in water for an unprotected diver?

A temperature that feels comfortable in air quickly becomes uncomfortable in water primarily because water absorbs heat from the body much faster than air can. This phenomenon occurs due to the unique thermal properties of water, including its higher thermal conductivity. When a diver is submerged, their body heat is lost rapidly to the surrounding water, which can lead to a feeling of chill even at temperatures that would be perceived as warm in air.

The rate of heat loss in water is significantly greater than in air due to its density and capability to transfer heat. While the other options touch on various aspects of temperature and pressure, they do not directly address the primary reason for discomfort, which is the efficient heat absorption of water from the body. As a result, even slight variations in temperature can have a much more pronounced effect on comfort levels in water compared to air.