DETROIT LAKES — "You've got people that always want to be the first one on the ice every year," said Gary "Seal" Thompson of Tri-State Diving in Detroit Lakes.

There are few who know more about going under the ice than Thompson.

"I've been doing salvage work for just about 40 years now," he said.

He's retrieved hundreds of vehicles that have plunged into frozen water over those four decades.

"We've had as many as three in one day."

You'd be wise to heed his advice. "You can have three inches of ice next to a foot of ice that's stronger than the foot of ice," he said.

As Thompson likes to put it, there's no such thing as safe ice, but milky, cloudy ice or ice with water on it is best to avoid completely. The DNR recommends staying off the ice completely until it measures four inches. Don't think about driving with a small car until it reaches eight inches, and you need at least a foot for larger vehicles.

When the ice is thick enough to support vehicles, Thompson said it's important to move slowly.

"Five to 10 miles per hour and 10 would be max driving on it. It creates a wave under the ice and the bigger the vehicle, the faster you go, it can crack the ice."

Thompson averages one recovery per week throughout the winter, but if you listen to his advice, it's less likely you could be one of them.