Between which depths does the greatest relative pressure change in sea water take place?

The greatest relative pressure change in seawater occurs between depths of 0 and 33 feet primarily due to the fact that water is approximately incompressible, and for every 33 feet of seawater, the pressure increases by one atmosphere (about 14.7 psi). This means that at depths greater than 33 feet, pressures continue to rise, but the relative change compared to the previous 0-33 feet section is significant because it's the first substantial increase in pressure experienced by a diver.

In this context, beyond 33 feet, while pressure continues to increase, the change per 33 feet is a consistent scale of one additional atmosphere, which is why the initial rise to that level is particularly notable. At depths shallower than 33 feet, such as 0-10 or 0-20 feet, the incremental pressure changes are less representative of the entire scuba diving experience, making the 0-33 foot range a critical depth to understand how pressure affects the body and equipment during dives. Thus, understanding the transition in pressure at the 0-33 foot mark is essential for divers in terms of buoyancy control, equalization, and overall dive planning.