As you dive deeper underwater, both the pressure and weight of water increase. This increase in pressure is due to the weight of the water column above you pressing down. The deeper you go, the greater the weight of the water above, resulting in higher pressure.
Pressure is defined as force per unit area, and in this case, it refers to the force exerted by the water on a given surface area. The unit commonly used to measure pressure is the Pascal (Pa) or its multiples, such as kilopascals (kPa) or atmospheres (atm). At sea level, the average atmospheric pressure is approximately 101.3 kPa or 1 atm.
For every 10 meters of depth in water, the pressure increases by approximately 1 atmosphere or 101.3 kPa. Therefore, at a depth of 10 meters underwater, the pressure is about 2 atmospheres or 202.6 kPa, and at a depth of 20 meters, it is about 3 atmospheres or 303.9 kPa, and so on.
The increased pressure affects both water and air differently. Water is relatively incompressible, meaning its volume changes very little under pressure. Therefore, as you dive deeper, the weight of the water column above you increases, but the density and weight of the water itself remain relatively constant.
On the other hand, air is compressible, and its volume decreases under increasing pressure. As you descend underwater, the pressure on your body and the air spaces within it (such as your lungs, sinuses, and middle ear) increases. This can cause the air spaces to compress, which can be particularly noticeable in the ears and can be equalized by techniques like swallowing, yawning, or using the Valsalva maneuver.
It's important to note that the increase in pressure with depth can have significant implications for diving, as it affects the body's physiology and the behavior of gases dissolved in body tissues. Divers need to carefully manage and control the pressure changes to avoid conditions such as decompression sickness or lung barotrauma.
Overall, as you dive deeper, the pressure of water increases, while the weight of both water and air also increases.