As the ice fisherman or curious youth ventures out on the frozen water, the initial steps are taken with due caution, listening for cracking sounds and sensing the ice density from reverberations on the soles of their feet. It seems fine. The ice is solid, and it's safe to go further. A few more steps are taken with less concern, but then a sudden break through. After the initial shock of hitting the frigid waters, the instinct to survive takes over. However, at the extreme temperatures survival won't exceed 15 minutes unless the individual can remain afloat and pull themselves from the hole. The recent string of sub-freezing temperatures has caused ice to start forming along the lakeshore and inland waters. With the ice comes the lure of ice fishing and the irresistible temptation to explore the virgin surfaces.

According to Chief Boatswainsmate William Mosgrober, who directs the U.S. Coast Guard's ice rescue response from Station Rochester, ice formation is determined by several factors including temperature, water depth, thermoclines, snow cover and wind conditions.

"Ice can form at different rates in the same general location," Mosgrober said. "You could have foot-thick ice in one spot and a short distance away the ice may only be a couple of inches thick."

Mosgrober said that ice along the shoreline can be weaker because of pressure. That pressure can bend and push the ice sheet against the shore and break it, forcing the surface to refreeze. Ice on rivers, creeks and streams can also be treacherous because of the currents at work under the ice.

For these reasons the Coast Guard has taken the position that no natural ice surface is safe ice and recommends against venturing offshore. While the recommendation may be prudent, Mosgrober concedes the practical reality is that ice will always entice people to venture out to fish, recreate or explore.

If someone is intent on going out on the ice, the Coast Guard recommends that they always wear a life jacket, floatation coat or survival suit. The lifesaving service suggests that no one goes out on the ice alone.

"At a minimum, ice fishermen, sports enthusiasts and the like should tell a family member or neighbor where they are going and when they plan to return," Mosgrober advised.

Perhaps most importantly, people need to exercise extreme caution and common sense. Whenever they contemplate going out on a natural ice surface, they should be keenly aware of their surroundings, the weather conditions, and wind direction. "We'll never be able to discourage people from walking on ice, but hopefully we can minimize the tragedies which occur every year," Mosgrober said.