I supply all of the specilized equipment for ice diving. (harnesses, ropes, ice anchors, chain saw, etc)
You will need a full scuba rig and a dry suit. It is not necessary to have redundant air supplies, but an H or Y valve with 2 regulators is highly recommended. Also the regulators need to be envronmentally sealed to help prevent freezing and free flow. I use a pair of Sherwood Oasis+ regs that I have had for many years. They have never frozen up on me.
You will need a dry suit. (though I have seen one person ice dive in a wet suit, he was a 400lb Wisconsin boy)
For undergarment you will need 2-3 layers. NO COTTON, it will only make you freeze. I use merino wool long johns as my base layer and then expedition grade polypro as the 2nd layer and then a 200gm Northface fleece as a 3rd layer. For the feet, I use neoprene socks designed for fishing waders and then a pair of wool socks over those.
For the head, I use a Henderson Ice cap underneath my regluar hood. You can go without, but this will keep you from getting an Ice Cream headache from hell. The temp under freshwater ice is about 35-37F, I dove the with the ice cap in Antarctica where the water temp was 30F and never got a cold head.
For hands, I like dry gloves. You can use thick wet gloves and preheat them with warm water. Either of these work about the same.
For the most part the temperature will dictate how long your dives are. 20 minutes is quite a while, I have done an hour, but was really cold. You can get just as cold diving in 45F water in PK as you can under the ice, it just takes about 20 minutes longer. For me it always seems to be the hands that limit my bottom time. They seem to get coldest first.
here is a link from my first couple of experiences ice diving.
Randy Cook's Home Page
Randy
