Deep Diving: Rules, Recommendations And Fun Facts

Michael,

Thanks so much for this!

I’m just get to learn some new things to you buddies although I choose recreational dive and now I’m almost finishing my Rescue course and i hope to continue go up in exploring world of diving so any changes can come on future.Thanks

The definition of a deep recreational dive is typically ‘deeper than 18m/60ft’, but this depends on the training agency. The largest agencies use 18m/60ft.

The maximum depth limit for recreational diving is also training agency dependant. Again, for the largest agencies, it is 40m/130ft. BSAC and CMAS allow dives to 50m, with non-accelerated decompression stops, as part of their recreational syllabus.
In technical diving, there is no definition of a ‘deep dive’. Extended Range level is 50-55m (dependant on agency). This limit exists due to issues with oxygen toxity. Beyond this level, helium is added to breathing gas to offset oxygen toxicity issues, as well as narcosis.

Nitrogen bubbles are not “usually trapped in the joints”, but rather, the symptom of pain-only (type I DCI) is felt radiating from joints due to nerve compression. Like sciatica, the localization of pain does not necessarily occur at the area of damage. For recreational divers, bubbles are often located in, or close by, major blood supplies. That also means they are often located in proximity to major nerves.
Divers are not treated with Hyperbaric Oxygen Therapy (HBOT), as this term describes a different treatment, specific for other ailements;; such as burns or some diseases. DCI treatment is run to specific schedule (table) of recompression/decompression in a hyperbaric chamber, in combination with breathing oxygen to accelerate off-gassing and critial bubble collapse, rehydration through drip and immune-suppresent/anti-coagulant drugs.

Nitrogen narcosis is not caused by the volume of saturated nitrogen, but rather the relative pressure of the nitrogen. In particular, it is linked with high nitrogen partial pressure in the lipid (fatty) cells of the brain, where it is believed to inhibit mental processes in an anasthetic process.
Strictly speaking, a tank left at safety stop depth cannot be described as a ‘decompression tank’ as it’s purpose is not for planned decompression. They are, more generally, called a ‘safety’ or ‘drop’ tank… and allow low-on-air divers to complete their recommended safety stops in comfort. As an emergency resource, they also allow emergency stops to be completed if the diver over-stays their planned dive times at depth.

The Advanced Open Water course does not ‘train’ to 30m/100ft. The deep dive conducted on that course increases diver experience and fulfills agency advice regarding the RECOMMENDATION for “newly certified Open Water divers” to limit their dives to 18m/60ft. There is no specific deep dive training or new skills on the AOW course, so it can neither train nor qualify you for deeper depths. Also, as mentioned in the article, a deep dive is any dive below 18m/60ft… the AOW deep dive does not have to be to 30m/100ft… and thus, the qualification cannot ‘train’ you to that depth. Divers are limited by their training and experience… if they only did a 19m deep dive on AOW, then that is the limit of their training and experience…

Deflating your BCD on ascent is possibly confusing. The diver should retain neutral buoyancy throughout the dive. On ascent, that means expelling excess air as it expands. “Deflating the BCD”gives the impression that the diver should EMPTY their BCD… and ascend negatively buoyant. This jeapordised safety and can cause a more significant buoyancy problem when they reach safety stop and then need to add air to get neutral again.

There is no “deep coral reef” in the Belize Blue Hole. It is a sheer wall, that becomes an underhang at approx 44m. Stalactites descend from that underhang… to a depth of 55 – 60m. The bottom is well below that, under sheer walls, no slope. Local diving operations routinely take under-qualified recreational divers below their maximum depths to see the stalacties. It is a very dangerous practice.

The world records for the deepest, and deepest wreck, dives have both been superceeded. The records stated in the article are many years out of date.

Hi and thanks for the answer. I know, and like, the deal with shallow diving, especially for shooting pictures, still I want to go deep :-9

Your answer was very helpful. I think I’ll start out by doing the one at 100 ft and see if I need more right away. I’m going to Egypt in a few month and thinking of doing it there. I heard good about a scuba school there.

“The air in your tank will become denser as you go deeper”
This isn’t quite correct (as your tank shouldn’t be changing size), it is the air in your lungs that becomes more dense.
Apart from that minor error, there’s some good advise there. IMHO it’s vital that we understand the risks before progressing our depths, and not just race deeper “because we can”