Ice diving

Ice diving is a type of penetration diving where the dive takes place under ice.cite book |title=AAUS Polar Diving Workshop Proceedings |author=Lang, M.A. & J. R. Stewart (eds.). |year=1992 |publisher=Scripps Institution of Oceanography, La Jolla, CA |location=United States |pages=100 |url=http://archive.rubicon-foundation.org/4240 |accessdate=2008-08-07 ] cite book |title=Proceedings of the International Polar Diving Workshop. |author=Lang, M.A. and M.D.J. Sayer (eds.) |year=2007 |publisher=Smithsonian Institution |location=Svalbard |pages=213 |url=http://archive.rubicon-foundation.org/5002 |accessdate=2008-08-07 ] Because diving under ice places the diver in an overhead environment typically with only a single entry/exit point, it is considered an advanced type of diving requiring special training (although whether it constitutes "technical diving" is part of a wider debate within the diving community). Ice Diving should not be attempted by anyone not trained (or in training) by a qualified instructor.

This special training includes learning about how ice forms, how to recognize unsafe ice conditions, dive site preparation, equipment requirements, and safety drills. Ice divers are tethered for safety. What this means is that the diver is wearing a special harness under his/her scuba unit. A line is secured to this harness and the other end of the line is secured to the surface by one of a number of methods.

Ice diving is a team diving activity because the divers line requires a line tender. This person is responsible for playing out and taking in line so that the diver does not get tangled. Communication to the diver, or to the surface, is accomplished by pulling on the line. Each series of tugs means a different thing. There is a diver suited up and ready to enter the water at a moment's notice. This diver is a safety diver, and has his own tender. His purpose is to assist the primary diver in the event of a problem.

Training

*How to impact the underside of the surface ice if the diver's weight belt falls off for any reason and the diver ascends uncontrollably and rapidly.
*How to deal with a frozen air supply system using a redundant back up system.
*What to do in the event the diver loses contact with the line or the line tender does not get feedback from the diver in response to signals given to the diver.

Equipment

Since diving under the ice takes place in cold climates, there is typically a large amount of equipment required. Besides each person's clothing and exposure protection requirements; including spare mitts and socks, there is basic scuba gear, back up scuba gear, tools to cut a hole in the ice, snow removal tools, safety gear, some type of shelter, lines, and refreshmentsFact|date=March 2008 required.

Procedures and precautions

* use a snow shovel to clear the snow and ice from the area.
* use an ice saw or a chain saw to cut a hole in the ice.
* use a weatherproof area for the divers to suit up.
* use a diving regulator suitable for cold water use. All regulators have a risk of freezing and free flowing - in this case the diver should immediately return to the surface. Some models fare better than others. Good practice - two unfreezing regulators arranged as following: first stage number 1 with primary second stage, BCD inflation hose and Submersible Pressure Gauges, first stage number 2 with secondary second stage (octopus), dry suit inflation hose and Submersible Pressure Gauges.
* connect the diver and tender on the surface with a rope and harness. The harness is typically put on over the dry suit but under the BC or other buoyancy device so that the diver remains tethered even if he or she must remove his or her air cylinder or buoyancy control device. The harness fits over the shoulders and around the back such that the tender on the surface can, in an emergency, haul an unconscious diver back to the hole.
* use rope signals.
* have a standby rescue, roped diver ready on the surface.
* have one or two divers diving at the same time from the same hole, each with their own ropes. Using two ropes runs little risk of getting tangled together, but using three significantly increases this risk.

Exposure Suits

Because of the water temperature (about 4°C in fresh water) exposure suits are mandatory.cite book |title=AAUS Proceedings of Special Sesson on Coldwater Diving. |author=Lang, M.A. & Mitchell, C.T. (ed) |year=1987 |publisher=University of Washington, Seattle, WA. |location=United States |pages=122 |url=http://archive.rubicon-foundation.org/4239 |accessdate=2008-08-07 ] Some consider a dry suit mandatory (neoprene dry suits are recommended); however, a thick wetsuit is also sufficient for hardier divers. A wetsuit can be pre-heated by pouring warm water into the suit. A hood and gloves (recommended 3-finger mitts or dry gloves w/rings) are mandatory, and dry suit divers have the option of using hoods and gloves that keep their head and hands dry. Some prefer a to use a full face diving mask to essentially eliminate any contact with the cold water.The biggest draw back to using a wet suit is the chilling effect of the water evaporating off the suit has on the diver. This can be reduced by using a heated shelter.Outfit Recommendations:
* Warm waterproof shoes.
* Warm anorak for cold weather.
* Warm cap covering the ears.
* Sunglasses with a UV filter to protect the eyes in sunny days.
* Lip care stick and cream to protect hands and face against cold and wind.

References

External links

* [http://oceanexplorer.noaa.gov/explorations/05arctic/logs/july24/july24.html Diving Under Arctic Ice]
* [http://scilib.ucsd.edu/sio/nsf/index.html Diving Under Antarctic Ice]
* [http://www.divinglore.com/RecreationalColdWaterDiving.htm Diving In Cold Water Conditions]
* [http://www.divingfinder.com/Scuba_Diving/Asia/Russia/Vacation-Holiday/Arctic_Circle_Dive_Centre Ice Diving, White Sea]