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Wisconsin Natural Resources magazine

Wisconsin Natural Resources magazine

Looking up from down under the ice. Fish circle near the triangular diving hole. © Alan W. Pahnke
Looking up from down under the ice. Fish circle near the triangular diving hole. © Alan W. Pahnke

December 2004

The glass ceiling

Winter diving opens a window to life under the ice.

Alan W. Pahnke

Preparing the surface | Taking the cool journey
Exploring a quiet winter world
Diving for pleasure and "treasure"
Rescue and salvage dives | Taking the plunge

With a couple of friends, I pulled the blue plastic sled piled with equipment across the frozen lake, calculating where the best spot would be. I had been here during the summer and knew we wanted to be in about 25 feet of water, so I picked a spot straight out from the boat landing. This would give us the needed depth, but still provide access to the weed beds where the bluegills had been in warmer weather.

Drilling the first hole through the ice is always exciting and all anticipation. Once the auger cut through, we judged the ice thickness, water clarity and depth to the bottom.

We drilled two more holes each 10 feet apart to form a triangle. There were five of us, but three holes were enough: Instead of angling, we were there to dive below the ice and swim with, not catch, those 'gills.

Preparing the surface

Good ice conditions and careful pre-dive preparations contribute to successful outings under the frozen ceiling. We like to have at least six inches of solid, clear ice to stand on. When divers don all their gear and a support team is stationed at the surface there's a fair amount of weight concentrated in a small area; we feel a half-foot of ice is the minimum thickness necessary to safely support the weight.

Everyone has a job to do. We start by shoveling snow away from the area where we drilled the holes. One person starts laying out and inspecting nylon safety lines. Another keeps shoveling snow. Two of us set up the diving equipment. The last person starts "connecting the dots" by carefully cutting through the ice between the holes with a chain saw. After the icy triangle has been cut loose, everyone pitches in to pull the block of ice from the water. Some divers push the block under the ice and retrieve it later to replug the surface.

Clearing the snow off the ice provides light to the divers underwater. A ring around the entrance hole is shoveled in a 100-foot radius to give the divers a point of reference while underwater. Radiating spokes are shoveled from the outer ring toward the entrance hole with arrows pointing towards the open water exit. These spokes and arrows are visible while diving underwater and show the diver the way out should he become unhooked from his safety line.

My buddy and I start suiting up and checking our equipment. A third diver also suits up and stands by with all his scuba gear at the ready in case of emergency. This is standard practice and part of the dive plan we always follow.

Before entering the water, we don either wet suits or dry suits. Wet suits allow a very thin layer of water to seep under the neoprene, to be warmed by your body heat. While a wet suit will keep one relatively warm during a short 20-minute dive, most ice divers in Wisconsin prefer dry suits. A dry suit traps a layer of air between the suit and your body. Air is a better insulator than water, so a dry suit is warmer than a wet suit. Dry suits keep you bone dry, and you can wear thin layers of clothing underneath. Clad in a full, hooded suit, booties, fins and dive gloves, you have only a small amount of skin exposed around your dive mask. You stay quite comfortable, even while swimming in 33F water.

Safety harnesses are a must. Ours are made of nylon webbing and are worn like a vest over the dry suit and under the scuba gear. Metal rings on the safety harness provide a secure place to attach the safety rope with a locking carabiner. A 100-foot safety rope is hooked onto the diver. This rope will be payed out by the line tender, who stays in communication with those under water. The other end of the safety rope is attached to a non-movable object above the water, preferably a stake that can be screwed into the ice as opposed to a car bumper that could give the divers a pretty quick and dangerous ride to the surface should the vehicle be driven away.

Taking the cool journey

With a safety diver standing by and our gear all checked out, we're ready to go.

Your perspective changes immediately as you first enter the water. On top of the ice, you get long vistas across expanses of snow and lots of sky, but once you slip into the water and are floating at the surface, you are confronted and surrounded by a wall of ice. You can't help but look at the ice in cross section, noting how small bubbles were trapped as each small layer formed. Then, as you start to descend, your own air bubbles slide along just under the ice like rolling pools of mercury.

The first sensation is the cold on the exposed part of your face. It stings a little, but that feeling slowly gives way to the same type of numbness you get whenever you are outside on a cold day. Next, you sense the light and clarity of the water. As the ice forms, the water settles down and particles suspended in the water sink to the bottom; visibility is often better than in the summer. There are no boats to roil the water.

There's a surprising amount of light beneath the surface; we can see about 20 feet. Since there isn't any wave action, the water remains clear and greenish. We take along flashlights in case there's something we want to investigate in dark shadows, but for the most part there is plenty of light from above. My buddy, attached to me by a 10-foot rope, kept an eye out for the bluegills that were so abundant during the summer.

We dive in pairs, tethered together to a safety line. We check in with our line tender on the surface once a minute, using standard signals to communicate. One pull means we are OK. Two pulls means give me some more line. Three or more pulls means "bring me back in," which can be fun, a bit like water skiing under water.

While divers are under the ice, another rope is attached to a safety diver. In the unlikely event of a problem underwater, that diver is ready to help out.

Should a diver get lost, the safety diver is attached to a rope that is twice as long as the sport diver's line. If a diver becomes unattached from a safety line, he or she is instructed to ascend to the surface and stay put. The safety diver will then swim out as far as his rope allows and begin a sweep just under the ice. This will bring the rope to the lost diver who can use it to find his way back to the hole.

As we descend deeper, the water pressure starts to squeeze the air in my dry suit. I add air pressure using the valve hooked up to my tank to compensate for the added water pressure.

After orienting ourselves with a compass, we check the underside of the ice, the safety rope, and the bottom before we begin slowly swimming around. If the bottom is silty, we stay above it so our leg kicks and fins won't stir up sediment and cloud the water. We look for obstructions that might tangle the safety rope and we take visual bearings to stay oriented.

A normal ice dive lasts 15 minutes to an hour. The duration is based on the comfort level of each diver. Divers in wet suits will get cold faster than those in dry suits.

If you've had any dive training, you will remember that there are established time/depth limits for all scuba dives. All ice divers begin with a full tank of compressed air, typically an 80 cubic foot tank filled with 3000 psi air. Divers practice the "rule of thirds" – one-third of the air is used for the dive, one-third for the ascent and one-third as a back-up safety precaution. On some river dives, the bed may only be six feet or so down, while in deeper quarries it may drop 60 feet or more. We adjust ascent times accordingly.

An ice dive actually begins in a classroom. A certified ice diving instructor leads the student in planning and carrying out each dive. All of the rules of normal scuba diving must be adhered to, and special consideration must be given to what's going on above the ice as well as below. For instance, the number of divers in the water at any one time determines the size of the hole; there has to be enough room so all divers in the water can surface at any time during the dive.

Additional safety rules and more planning apply to cave diving and penetrating shipwrecks; you have to allow for the fact that you simply can't swim directly to the surface for air.

In the classroom, the instructor explains the technical issues that apply to the dive. Training emphasizes safe techniques for both the diver and the surface support team. The instructor must ensure everyone understands his or her various job duties while on the ice. Students venture out onto the ice only when the instructor is confident they know the procedures for conducting a safe dive.

Exploring a quiet winter world

Not seeing any bluegills, I looked back over my shoulder toward the entrance hole. Our safety line was visible all the way to the hole, but I couldn't see the line tender who had just signaled me with a pull on the rope. I gave a pull back to let him know we were OK. I used a hand signal to my buddy to let him know we were going to swim south to a deeper part of the lake. I wanted to check out the bottom composition to be sure it was suitable for a fish crib we were going to put in after the dives.

As we descended, the line tender payed out all 100 feet of our safety line. Having reached the end of our rope, we began a sweep of the lake bottom to see the terrain. We swam in an arc proceeding to shallower water where weeds grew in the summer providing bluegill habitat. I was hoping to see some, but nothing was moving during this dive.

I checked the air pressure in my tank and signaled to my buddy that it was time to return to the surface and let the other divers have some fun. We decided to ascend to the underside of the ice and swim back to the hole. Scuba divers are taught to ascend slowly, look up and hold their hands above their head as they rise. There are times when divers forget to put their hands up and bump their heads on the ice. There's some good-natured teasing when that detail of the dive is shared with the others.

Approaching the ice I looked up and saw my bubbles flatten out like liquid silver as they hit the smooth underside. I ran my hand through them and they scattered into smaller bubbles before regrouping to form large pools of air.

With clear ice and no snow cover, ice divers can see their teammates on the surface. Team members work together to prepare for the dive and provide mutual safety. © Alan W. Pahnke
With clear ice and no snow cover, ice divers can see their teammates on the surface. Team members work together to prepare for the dive and provide mutual safety.

© Alan W. Pahnke

Looking up from down below offers other interesting perspectives. You can actually see the shadows of people standing on the ice, especially over the shoveled spokes and rings.

Following the safety line back, we surfaced in the hole. After getting help to get out of the water and taking off our equipment, we answered questions from onlookers who stopped by to see what was going on. As I explained what the next team was doing, we made sure their safety lines were attached and the lines were not tangled. Then it was my turn to handle the ropes and communicate with the two divers underwater.

We usually dive on warmer winter days, but sometimes we'll have a shanty with a propane heater, a nearby van or some other shelter for changing back into boots, jackets and hats.

When all the divers have had a turn and all our gear is packed up, we slide the ice blocks back into the hole, shovel snow into the cracks so the water will freeze, stick boards into the sides of the cracks, mound snow around the boards and mark the site well so it will be seen by others traveling on the ice. We'll come back after the ice has frozen, remove the boards and level out any rough spots.

Diving for pleasure and "treasure"

Our diving group begins the year with a New Year's Day dive in the Fox River in Menasha, to look for old bottles from days when the river was used as a dump. We end our dive year in December with the Pearl Harbor Day dive in Fish Creek, gliding between the marina piers in search of anything that may have dropped overboard.

Ice divers also explore rivers, quarries, lakes and manmade ponds. There's a shipwreck in Little Sturgeon Bay that is accessible to ice divers, as are many marinas in Green Bay and Lake Michigan. It's fun to find items that went overboard during the warm boating months. A friend of mine found a small Mercury outboard motor in the Menominee River and is using it to this day on a lake in northern Wisconsin. Towels, boat brushes, flags and small anchors are more common finds. We also help out and remove any hazards we can safely lift, and notify authorities when we find heavier or more dangerous items – like the time a friend found an old unexploded artillery shell.

Wild sights under the ice are always a pleasant surprise. Some of the largest trout I have ever seen are in a private quarry in Amberg. The quarry owner comes out after the hole is opened and feeds the trout hot dogs. The fish will actually swim onto the ice to get at the food. These trout are really curious and will swim right up to your mask to see what is going on. They seem a little slow in the cold water, but once the divers get into the water the fish loosen up a little and will take food right out of your hand. This same quarry bed is littered with mining tools. You can find an old ore cart and the rails used to haul out gray granite.

Rescue and salvage dives

Most ice diving is done for adventure, but it is also a serious business. Many times divers are called in when a car or snowmobile breaks through the ice. Speed is of the essence and certified rescue ice divers must work quickly to save lives. Usually rescue diving is done solo to keep safety lines from tangling. I can tell you the cold water can be a lonely place when the visibility may be as little as four inches and you know any time you might come upon a body. As a law enforcement officer, I've been on a number of dives looking for both bodies and evidence of crimes. This type of diving takes a special person, and fortunately there are men and women who volunteer for this duty with their local sheriff's department.

We apply the same safety rules for emergency night dives, only we try to shine as much light as possible onto the ice. This might include angling car lights onto the ice, bringing in portable generators and light banks from fire departments, or employing underwater flashlights and strobes attached to the diver. The highly trained diver has to stay focused. Despite the tension of an underwater night emergency, you can't afford to panic and you need to stay safe and systematic if you are going to help someone.

Pulling an empty car, snowmobile or other property out of the water may lack the urgency of a human rescue, but safety is still important for salvage divers. There's usually more time to set up and attach hauling lines. Special wreckers equipped with pontoons can safely handle the job if the ice gives way.

Some commercial diving is scheduled in winter when the ice provides a steady platform to set up equipment over an opening. For instance, one of the best times to clean zebra mussel infestations from municipal water supply intake pipes is in winter. Pile driving for piers, bridges and other over-water construction often starts in winter, and divers are employed for some phases of these projects. Winter work may also include clearing frozen intake pipes at power plants, inspecting ship hulls for damage and checking for breaks or damage to underwater cables. For these longer dives, commercial divers may wear special warm-water suits, which circulate heated water from the surface through a hose attached to the suit to insulate the diver from the cold.

Taking the plunge

Ice diving opens up a whole new world in winter. After they complete a couple of training dives, most divers who take the plunge become less apprehensive and are more relaxed. Like any new experience, there are a lot of unknowns. As long as you stay safe and safety conscious, these concerns quickly dissipate once you are in the water, weightlessly swimming or lying on your back on a lake bottom watching your air bubbles rise to the surface. It can feel just as relaxing as if you were in 80F water on a tropical Caribbean reef.

Don't believe me? Well, don't hesitate to have a chat with ice divers should you see a group of people standing on a lake or pond with brightly colored scuba tanks lying about in February. Divers are very friendly people and will be happy to explain their sport to anyone who asks – even if you don't think a brisk dunk in the frozen drink is your cup of tea.

Alan W. Pahnke is an ice diving instructor from Suamico and a Lieutenant in the Brown County Sheriff's office.