Which pressure is most relevant to divers when measuring depth?

The most relevant pressure for divers when measuring depth is gauge pressure. This is because gauge pressure specifically reflects the pressure exerted by the water column above a diver, excluding the ambient atmospheric pressure at the surface. As a diver descends, the gauge pressure increases, indicating the depth of water above them, and thus helps in determining their current depth.

Gauge pressure is essential for divers to monitor, as it allows them to keep track of their ascent and descent, ensuring they stay within safe depth limits and manage factors such as nitrogen absorption during their dive.

While absolute pressure does include atmospheric pressure and is relevant in a broader context, it is gauge pressure that directly corresponds to the depth measurement that divers need to be most concerned with. Atmospheric pressure is constant at the surface, and while hydrostatic pressure is a related concept, it is often discussed in terms of the effects of fluid at depth rather than as a direct measurement tool for divers.