The lure of diving deep is there. Cruising at 100' on a wall
in the tropics that descends to 3000' has a mystical attraction to most
divers. The temptation to descend further is so inviting it becomes dangerous.
Is it the exhilarating feeling obtained when one cheats death or just plain
nitrogen narcosis? With the introduction of computers more and more
divers are taking the plunge to dangerous depths. The decompression tables
would not allow extremely deep dives because of the lengthy stops that had
to be made on the way to the surface.
Many feel the maximum depth for an experienced diver
should remain at 130 feet. There are many reasons for that limit:
The pressure at 132' is 5 atmospheres absolute. The oxygen breathed at that
depth is at a partial pressure of 1.05 atmospheres. At deeper depths oxygen
poisoning becomes a real possibility.
A diver's air supply is cut to 1/5 of its normal amount.
Nitrogen is at a high enough partial pressure to cause significant intoxication.
Any contamination in the air supply, such as carbon monoxide, carbon dioxide,
oil vapors, etc. are 5 times more concentrated.
Decompression may be required since the bottom time limits for that depth
is only 10 minutes, and that counts the time descending.
It is darker and devoid of most color.
Because there is less light, there is less life.
And, if an emergency should occur getting to the surface at 1 foot per second
is quite difficult.