Ice Diving is a type of penetration diving where the dive takes place under ice. Because diving under ice places the diver in an overhead locked environment, typically with only a single entry/exit point,, it is considered an advanced type of diving requiring special training. 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 diver's 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 another 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 that deals with specific problems that can be encountered under ice can be:
- 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.
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 refreshments required.
Normal procedures and precautions for ice diving are:
- 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.
- 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 diver roped and 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.