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What happens when the Lake Freezes Over?

If you're anything like me, you're one of those curious-about-everything types. I have wondered about this subject for plenty of years, but just recently did some reading on it. First off, I learned a lot about the science behind a lake freezing. Second, I learned what happens to the wildlife living under that sheet of ice. And third, I learned about what to do and what not to do surrounding a frozen lake (ok, some of that came from experience). Let's dig in...

Minocqua Wi frozen lake


If heat rises, how is it possible that the uppermost layer of a lake is the layer that freezes during the winter? Well, the short of it is that frozen water is less dense than cold water which creates ice "floating" on top of the lake. It actually has to do with the hydrogen atom and how it bonds. Well, I tried...and tried (and deleted many times) to describe this concept, but decided that a video would be more effective is explaining. Here goes...

So as you can see from the video, water is unique in that as it freezes, instead of contracting, it expands creating beautiful ice crystals in complex hexagonal shapes that happen to be lighter than cold water.

During the winter, all of the lake water drops in temperature but the water on top freezes when temps drop below 32­°F. This creates a blanket of ice or a frozen lake (like our beautiful Lake Minocqua pretty soon).


Well, that same sheet of ice covering the top of the water traps in oxygen which the fish and other critters use to sustain their lives throughout the winter. They significantly reduce their activities to minimize oxygen use and preserve their fat stores. Pan fish like the Bluegill and Sunfish will gravitate towards beds of vegetation for protection. Some fish will locate warm water pockets in the lake to hang out and feed. These are typically near warm water inlets (which make for good fishing but are very dangerous due to the thinned ice).

fish under water lake minocqua

So, fish still swim and breathe and eat and hide from predators even when the lake, being frozen completely, looks totally inactive. (oh the things you can learn on youtube)


As the managers of Nitschke's Northern Resort for many years, we have seen and heard our fair share of stories around what NOT to do on Lake Minocqua while it's frozen.

frozen lake in Minocqua WI

One in particular stands out...Never use a snowmobile, at high speeds, to cross over unfrozen pockets of water. It NEVER ends well. We watched a group of dare devils one time cross multiple sleds over the open water in the Kawaguesaga channel. One by one they sped as fast as their sleds would take them and they all made it to the other side which was frozen, except for that one guy. We all shook our heads, then assisted him of course, as he watched his poor sled sink to the bottom, drenched and shivering from the freezing cold lake water.

That, my friends is definitely what NOT to do on a frozen lake.

Let's delve into another "not" story. My daughter of all people, took a snowmobile out on Lake Minocqua when it was just barely frozen. (as she recounts AFTER the fact) She became worried about the dark spots she was crossing at a moderate speed, fearing the ice was too thin to hold her weight on the sled. She increased her speed significantly (ON MELTING ICE WITH NO SNOW) and ended up fish-tailing the back-end of the snow mobile, flipping it over her head, causing a concussion. Thankfully, she "came to" immediately, rode the snowmobile off the ice quickly and went home. Needless to say she got an ear-full from me on the way to Emergency room.

This is also a prime example of what NOT to do on a frozen lake.

So that leaves us with what TO do on a frozen lake... BE CAREFUL!

  • Never go out on the ice until you've confirmed with officials that it is safe to do so.

  • Be weary of warm water inlets.

  • Avoid areas of thin ice.

  • Always wear a helmet if you're going to be riding a snowmobile (anywhere, but especially on the ice).

  • Be a responsible ice-fisherman - understand what you are doing on the ice.

  • Be safe.

ice fishing Lake Minocqua

There you go...curiosity we all know what happens when Lake Minocqua, or any lake for that matter, freezes over.

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