Air compressibility under pressure

Air compressibility means gas occupies less space when you go deeper. This physical reality changes everything about your dive profile. As you descend to 30 m, the ambient pressure increases to 4 bar. Because of this, the air in your lungs and BCD shrinks significantly. You will notice your buoyancy drops quickly if you do not add air.

I saw many students struggle with this in Koh Tao. They often forget that air density increases alongside pressure. This makes your regulator harder to breathe at 35 m depths. Always check your air consumption rates during the first 5 m of descent. If you ignore this, you might run out of gas faster than expected. Watch your SPDI gauge closely while you descend.