It becomes wet.

It becomes wet.

Your body experiences an increase in ambient pressure of 3 atmospheres (atm), to a total ambient pressure of 4 atm. This requires you to equalise pressure in rigid body airspaces (primarily sinsues and middle ear). This is most simply achieved using the 'pinch-and-blow' (Valsalva manoeuvre).

Any exposure suit will be similarly affected by the increase in pressure. If it's a neoprene wetsuit, it will get thinner and thus become less buoyant. This will make you feel 'heavier' in the water, and is the primary reason why SCUBA divers wear buoyancy jackets, to compensate for the loss of suit buoyancy at depth. If it's a drysuit, the air within the drysuit will also be compressed, causing the suit to 'shrinkwrap' you, which is uncomfortable unless more air is added to the suit.

Light levels will also be affected by depth, in terms of both colour and intensity. In clear (usually tropical) water, the light intensity will be somewhat diminished, but everything will look very blue. In plan ...more