Sounds like you are having fun horsing around in the pool. This is good, get
comfortable in the water. But you are probably developing bad diving habits.
Dropping down as a diver is different. You will intentionally weight
yourself slightly negative so you do not have to work at getting down. If it
takes a lot of effort / energy just to drop you will use a lot of air doing
so. You will be a bit worked up once you reach depth and will continue to
use air at a higher rate, get cold faster and end the dive sooner as a
result. So for now play in the pool but don't try to develop any techniques
you think will help you learn to  dive, instead pick up the PADI course book
and review or get any one of many diving books from the library or a book
store.

John

It's a bit of a fine point, but you don't get neutral by stopping exhaling.
Other factors are at work, including kicking, skulling, whatever.  It makes
little difference in this case, but is a significant part of understanding
buoyancy which, as you learn more, will hopefully become a significant part
of your diving.

Then you weren't dropping because you were exhaling in the first place.
Something that is negatively buoyant, as you would be if your descent was
entirely due to your exhaling, does not become less negative without
increasing volume.  What sinks, keeps on sinking.  You were probably never
actually neutral, let alone negative.  You were simply close enough to
neutral that little effort was required to descend.  When you stopped making
any effort, you stopped descending.  If you had stopped all movement, you
probably would have slowly returned to the surface.

Resistance to descending decreases for sure.  Your buoyancy is directly
related to the relationship of your mass to the mass of the liquid you
displace.  If your body displaces liquid weighing more than you do, you
float.  If it displaces liquid weighing less than you do, you sink.  If you
displace liquid weighing just what you do, you're neutral.  What happens as
you descend, assuming you do not exhale, is that the deeper you go, the more
the gas in your lungs is compressed.  As that gas compresses, your body
displaces less water but still weighs the same.  You become less buoyant or,
if you prefer, more negative.  It's easier to descend.  You may actually
reach a depth where you cease being buoyant and become negative.  From that
point and deeper, if you stop doing anything, you'll sink, and keep right on
sinking until you do something about it.  The reverse is true as you ascend.
All else being equal, the gas in your lungs expands, displacing more water,
making you more buoyant or less negative.

This is intersting now.  It will be important later.  Most divers experience
a larger shift in buoyancy while diving than you do just swimming around.
The gas in the lungs is less significant because you're breathing compressed
gas from a tank.  You replace the volume in your lungs with more gas.  The
deeper you go, the more that same volume of gas is compressed and the more
it weighs, creating a slight tendency to become less buoyant with depth, but
there are other factors that are more significant.  One of them is the gas
in your thermal protection.  Dry suits and wetsuits both depend on gas for
insulation.  That gas compresses with depth.  In a dry suit, you can replace
it, just as you do in your lungs.  With a wetsuit, you can experience a
significant buoyancy shift as you descend or ascend, significant enough to
become a problem if you don't plan for it.  Divers have died because they
didn't realize that the lift provided by their wetsuit would disappear at
depth.  They become negative enough that they could not ascend.  Generally,
divers use buoyancy compenators of some kind to offset things like this.
Nothing is perfect and buoyancy compensators have been known to fail,
rarely, but it only takes once.  In such failures, those that don't ensure
that they either have backup buoyancy or that they can swim themselves and
their gear to the surface, become statistics.

On ascent, opposite effects occur.  As the wetsuit, etc. expand, the diver
become more buoyant.  If that buoyancy becomes greater than your ability to
slow your ascent, you're also well on your way to becoming a statistic.
This too is rare, but most often results from a diver's failure to account
for the change in buoyancy due to use of the gas in the tank.  A standard 80
cubic foot tank holds about 5 lbs of gas at the beginning of the dive.  When
that tank is empty, which we hope it never is during the dive, it's 5 lbs
more buoyant than it was at the beginning of the dive.  If you don't weight
to offset that, you're in for a big, and very unpleasant, surprise when you
begin your ascent.

At any rate, all of this begins to show what I was talking about when I
indicated that the difference in what you said about your trip to the bottom
of the pool was not a significant error for freedivers, but can become a
significant error if continued into your dive training.

It will also improve your cardio vascual fitness and improve your breathing
efficiency, both of which are good things for those at high altitudes.  For
the first few days at your altitude, I can't even walk up stairs.  I'm
flatland born and raised.

Not a bad plan.  Try to find one that dives himself.  Do a Google search on
"DAN" and contact them to see if there is one they recommend in your area.

Probably, but not for sure.  Some people really have to work to overcome the
body's natural tendency to hold the breathe during a dive.

Holding your breath while diving is a very bad thing.  You will probably
have to concentrate to learn not to do that.  Hints as to why are in my
prevoius discussion.  You'll learn more in your class.

Call it developing new habits more suitable for the different environment.

You're actually learning the easy way.  Those that learn the hard way are
called statistics.

Lee