improve down time

How do I improve the time I can stay under? Do I just practice holding my breath or are there specific exercises to do?

Fitness is, of course, key to your diving success, but relaxation is the path to longer bottom time.  Google "shallow water blackout" for some good info to know before pursuing the goal of having longer bottom time.   

How do I improve the time I can stay under? Do I just practice holding my breath or are there specific exercises to do?

Check out the Deeper Blue forum. It has a ton of info and links to literature, training programs, etc.
http://forums.deeperblue.com/
 

Thanks

Dive more

Come play Underwater Hockey. I guarantee improved bottom time and meeting some other pretty good divers.  I don't know where you are but it is played a few places in the bayarea. San Jose, Tues. Wed. Sunday  San Francisco, Mon. and Fri. Sebastapol Tues. and Thurs. 
  It is good practice, especially for diving in shallow in rough water.

Brian

Getting so that you're very comfortable and calm in the water is the first step.  Then fitness, training and gear come into play.  I leave my gun on the bottom (attached to a floatline), which allows me to descend faster and with less energy.  There are lots of little tricks. 

Also a lot of beginning divers don't breathe up long enough at the surface, you should breathe up for 2-3 minutes before diving again to ensure that your blood oxygen level has had time to recharge.  After about 15 minutes of bottom time an automatic reflex kicks in and pumps spare blood from the spleen into your veins and increases your oxygen capacity a bit too.  (I sometimes wonder if this is why older divers tend to have heart attacks while diving).

I ordered a freediving book from Amazon so I can study and practice. I have started reading on the net also. Explain breathing up.

I ordered a freediving book from Amazon so I can study and practice. I have started reading on the net also. Explain breathing up.

Deep controlled breathing at the surface, not hyperventilating. Get calm and relaxed and try to stay that way.

I saturate my bloodstream with O2 and remove CO2 by deep breathing or hyperventilating or whatever it's called.  In preparation for this season I've been doing laps at the pool.  After laps I hyperventilate at the edge of the pool and practice underwater swimming.  When I started a few weeks ago I could swim one pool length underwater.  Now I'm up to 1.5 lengths.

Practice swimming underwater, and relax.

I plan on diving with you this year Dave. I'm going to train for it.

I plan on diving with you this year Dave. I'm going to train for it.

Yeah, Man!  Go, Amphibian!!   

A lot, a very big amount of bottom time comes first from ones natural ability to hold vast amounts of oxygen in the lungs. This coupled with controlled relaxed breathing while on the surface( try yoga breathing) will increase your down time. Someone here already said it. Dive more often. I always notice that the first dive of the year tends to be a bit hurried and anxious. This depletes my stored oxygen faster than kicking down. Anxiety sucks while in the water. While realxed at the surface when I take my final breath in before the dive I try to fill my stomach with air. Consiously focusing on that part of my body. Next I try to imagine filling my middle chest to full capacity. Then the top of my lungs. Finally sipping in a bit of air. This is done without tension and after practiced a bit will become second nature. When turning to kick down I tuck , extend my legs into the air and let the weight of my belt and my legs push me down into the water. Only when my legs are and fins are under do I kick.  You have probably seen guys kicking in the air, not good. Then they are slow full kicks with my legs really extending. Usually four or five good strong kicks will propel me to the depth of twenty or so. As the air starts to compress in the cells of your wetsuit you will become heavier and thus start decending more rapidly without much effort. I think Dave W is a good example. He has a big chest which means he can probably hold more air that I can. Practice and relax. Craig

I started doing o2 and co2 drills and am going to start working in the pool tonight.

Just to be more clear about the description of hyperventilating vs slow controlled breathing, and associated risks. Guys have blacked out in pools, the ocean is less forgiving, gotta be careful. Read all you can for a good safe understanding.

(from wiki) In medicine, hyperventilation (or overbreathing) is the state of breathing faster and/or deeper than necessary, bringing about lightheadedness and other undesirable symptoms often associated with panic attacks. Hyperventilation can also be a response to metabolic acidosis, a condition that causes acidic blood pH levels.

Counterintuitively, such side effects are not precipitated by the sufferer's lack of oxygen or air. Rather, the hyperventilation itself reduces the carbon dioxide concentration of the blood to below its normal level, thereby raising the blood's pH value, initiating constriction of the blood vessels which supply the brain, and preventing the transport of certain electrolytes necessary for the function of the nervous system.[1]

Hyperventilation can, but does not necessarily always cause symptoms such as numbness or tingling in the hands, feet and lips, lightheadedness, dizziness, headache, chest pain, slurred speech and sometimes fainting, particularly when accompanied by the Valsalva maneuver. Sometimes hyperventilation is induced for these same effects.

There is nothing better overall than more watertime, those UW hockey guys are freediving animals! Seahunter and Bigeyedave are a couple of local hockey-jocks. Growing up hunting in the Islands Fuzz has the ability of a shark.

Spending time in the ocean, even my old out of shape body(bad thing) has more bottom time now than when I was younger and more fit. Mental calmness from feeling comfortable in the water. Because our local conditions are not as diver friendly, it takes a while to feel the peace.(ie. no-vis,rough water,fear of the unknown,being eaten )