Not many deco probs in that depth :p I would think getting trapped/entangled/cut/knocking your head/etc would be the biggests risks (not that its likely). The Just like anything, be careful and be aware and you should be fine I would think. Probably a lot safer than a lot of other things you can do though :p

You will be ok, just don't go in anywhere you can't get out of. From that depth a rapid ascent is no dramas. I must warn you i have done a couple of solo swims in 15-20m, does get pretty eerie down there on your own!

Rapid Asent no dramas bullshit .come on if your going to coment then get it right .you can get bent  coming up from 1m. Solo dives are as safe as you make them all the same rules apply .and take no chances .Check your anchor and let someone know where you are and times in and out .that will be a big help if something goes wrong.happy diving

(even if the way he types makes it hard to read :) )I have done one or two dives, I do a lot of them alone as I spear fish and feel that someone else with a spear gun is more dangerous to me then the dive itself...not that I would suggest it to others in most situations. Fact is that things are what you make of them, if you act right and do shit right your almost as safe as you would be with a buddy.

One thing I would say is if your not confident in the water and in your diving abilities then DONT dive alone. No matter what the depth, normally what causes accidents in the water is people that panic...from 1 to 10m you double pressure (halve a lung at atmospeheric pressure), true from 10 to 20 it halves again BUT it is going from half to quater not 1 to half...if you dont breath out from 5m you can do your lung damage...

Lot of risk involved in diving full stop but most can be minimised if you know what you are doing/dealing with....as Paul & WADRay have correctly have pointed out - massive pressure differential in shallow water! If you don't why you should/shouldn't be doing something - don't do it. That said, any diver with a reasonable amount of experience should be able to cope with most self rescue situations unless it involves a complete failure of your breathing system.....I solo dive a fair bit and have a 2nd air source for that reason. Just use your common sense.....  

Nothing to be too worried about if your confident and well planned and if your only diving 5 meters, as long as you manage your risks as best you can, as people have said, keep people informed, even log it with sea rescue, have someone on the boat to man a radio and watch your bubbles if you need to be located, check your anchor. dive safe and if your worried about getting stuck well dont put yourself in a situation where you'll get stuck.

Main thing also if your stressed about it or umming and arghhing on the day don't do it,as with all diving you want to be comfortable entering the water so you can focus on what your doing. no shame in calling a dive if your not up for it. can take bigger balls saying f@%k it in front of your mates than diving and making yourself a headache for someone else.

done a fair few solo dives, just know your limits, know the risks, and be aware that your safety is your own responsibility

As guys said said above yes biggest difference in pressure is the first ten meters. You need to remember if your need to reach the surface in an emergency you'll still need your weightbelt on and perform a controlled emerency swimming ascent(cesa) which you would'v done in your open water course from 6-9 meters depth anyway. to ditch your weights as a bouyant emergency ascent you'll surface too fast and fizz up something you should only do when you can't reach the surface and your options are either drown or come up with a decompression injury.

is in the first 10 metres, always watch your ascent rate especially in the 0 - 10 metre range

Not that I'm looking at going deep at all or even creating a habit of this, I am suprised at how many people seem to go solo! As fa as diving goes, I feel confident enough without cocky enough to double check myself. Just hope I see a few crays while down there now :)

- i did not intend to advise a bouyant ascent, rather if something goes wrong in 3-5m a reasonably quick approach to the boat will be ok(ie no deco obviously). I do not at all advocate a bouyant ascent(bcd inflation-weightbelt dumping) unless last resort which in that depth should not be required. Apologies for the confusion. Good luck oracle!

PS Greg Norman (aka the Shark) got the bends after his gear shat itself in 30 odd metres- he did a RA and had to spend a couple of days in a hyperbaric- lucky he could afford it!

say u have blown an ear drum as a teenager from coming up too quick from the depths, could i still do a dive ticket? and will it ever get in the way of diving at depth once experienced to do so?

cheers ben

if that means anything?! will have to look into it cheers

And would like to clarify some of the points raised.  Ok I understand the 10 metre pressure differential issue, but the comments about getting bent in one metre?

The pressure differential in that situation as others have pointed out could lead to a Lung expansion injury given that a held lungful of air at 5 metres would be 1.5 times larger at the surface.  Getting bent is decompression sickness relating to absorbtion of nitrogen into the bloodstream at depths, then an ascent that does not allow the nitrogen to dissipate from the bloodstream leading to the nitrogen falling out of solution on ascent - bubbles in the blood. 

Since the depth that Oracle is refering to is 5 metres, we do absorb nitrogen at this level, but it would take so long to accumulate to a dangerous level as to be nearly impossible.  This is why your safety stops are 3 minutes at 5 metres, because you are off gassing the whole time you begin your ascent. My eRDPml tells me that at 5 metres I have No Decompression Limit dive max of 219 minutes. Obviously your air becomes the limiting factor. The No Decompression Limit means that you do not have to decompress, which is basically allowing time to off gas the nitrogen.

Using rough rounding 21% for Oxygen and 79% Nitrogen at the surface (1bar/ata) the partial pressure of O2 would be 0.21 bar/ata and N2 0.79 bar/ata. This is the same as the tissues in the human body.  At 40 metres, the pressure is 5 bar/ata and the partial pressure of O2 would be 1.05 bar/ata and N2 would be 3.95 bar/ata and the tissues of the body will attempt to reach equilibrium with the air in the tank.  This is important because it means using air (21% O2 and 79% N2) at 40 metres the physiological effect on the body is as if you were breathing 100% oxygen at the surface. Of course O2 is consumed in the bodies respiratory process and nitrogen is not and that is why it concerns us.

At 1 metre, the pressure is only 1.1 bar/ata so partial pressure 0.231 bar/ata O2 and 0.869bar/ata N2. As gases will move from high pressure to low in an attempt for equilibrium the large pressure gradient in these partial pressures at  surface and 40 metres means gas absorbtion/dissipation is at a much higher rate than at the surface and 1.1 metres.

The confusion may lie due to first aid.  As both Lung expansion injuries and Decompression sickness require the same treatment they lump them together and refer to them as Decompression illness.

Well that all sounds just great but at the end of the day allways surface slowly regardless of depth ,even walking on the footpath has its risk .I have never read or been tald from any dive instructor or dive master that there is no risk in shallow water to 5m. but maybe im talking to the wrong people .

Look there is a lot of realy good info on here and i think most people are right to a degree
IMO and only in my opinion treat this dive as if you would treat any other dive and you will be ok.
If you are looking for crays (or hunting) their is a fair chance your buddy would be of no assistance if you were to get into trouble any way because he/she would be looking in a ledge or something anyway
I have done many hundreds of sole dives to 30m and survived without any problems if you do your checks and look after your gear.
Dive gear vary rarely fails and cuts off your air it usually free flows when it shits itself so you can assend safely with faulty gear if needed MOST DIVERS WHO GET INTO TROUBLE RUN OUT OF AIR BECAUSE THEY FORGET TO CHECK THEIR AIR and simply just run out then have to do a bouant accent Hence getting bent or lung trauma.
The main thing is to tell someone what and where or leave someone in your boat who knows your dive plan.

cheers for reply when first did injury to ear in 11m i can tell you once i rushed to the surface i couldnt even lift my head from the waterline little own stand! will have to do a doc check cheers

Ended up doing two dives. On both, I had a snorkler above me. Not for any real reason outside of they were there but to be honest, I really enjoyed the time on the bottom alone. First dive was only 4.5 meters at deepest, then the second went to a massive 6.5 meters. Saw a couple of rays, sambos, 2 seals swimming above my head playing in the bubbles and caught 5 out of 7 crays I spotted.

What a great couple of dives!

I was comfortable with where I was at (snorkeled around the area although not exactly here pre scuba), felt comfortable in my abilities and I just LOVE DIVING so had a blast. Will over take fishing for me soon I think - except in winter

Good to hear all went well and getting a few crays too

Its not a scary as you may think you just need to be careful

Finally be careful because it dose become addictive LOL

Well done mate, diving is addictive. I rarely dive "solo", but my buddy pairings on hunting dives are not what you would call stereotypical arrangements. If you can see each other throughout the dive, well thats a bonus.

If anyone is looking for mid week buddies, I'm pretty keen. Happy to share the load with boats as i've got one and being a stabi, really good dive boat. My main buddy is unavaiable for a while and I do like heading out with holkk when we can. Being a mid weeker, i'm good for Mon, Wed and Thurs mainly. Don't mind cray fishing or just viewing pleasures.  Most of my diving is done in 15-23 meters but I do have my open Advanced dive cert. If a few people were to head out for a night dive and/or swimming with sharks, this is something that I'm keen to learn soon. I'd like to think I'm ready for both but really scared shitless of either, let alone both at the same time. Few experienced divers around me would help.

Looking that that schedule, I'm usually up for Thursdays!

If you are looking for Grey Nurses- there are plenty at the Key Biscayne.

We had a dive on some new ground North of Narrow neck about 4 weeks ago which bottomed out at 25m. There was a cave that had 3 Grey Nurse swiming around in it. Was great to see with the biggest being 6-7ft. Have done alot of diving at Rotto but this is the first time I have come across them not that its uncommon. I believe they congregate around West End through Winter I guess breeding. Good luck it's a great experience swimming with them.

The cave is just inside one of the marker buoys out at west-end. I have dived it, The buoys are marking the No-fish area (i think) about 100m inside there is where "shark cave" is-SSSSHHHHHH!!!.

Another mid week diver here!!!!

hey till i dived the caves a few weeks back when water temps still up and there were maybe a dozen grey nurses hanging around. Not as many crays as i would have liked though.