Ice fishing is ubiquitous in Minnesota, home to the largest ice angler population in the nation.

Most of us don't give a second thought when thousands of ice fishing houses and thickly dressed anglers show up each winter on frozen lakes and rivers around the state.

That just happens here.

But it's also what makes us unique.

"Ice fishing is this really distinctive thing of living up north; people who don't live here think it's nutty," said Greg Breining of St. Paul.

And, of course, staring for hours into a faintly illuminated hole bored through the ice is a little bit nutty. But several hundred thousand of us do it anyway.

Breining, 56, a freelance writer, and friend Layne Kennedy, 51, a freelance photographer from Minneapolis, both long noticed that intriguing things happen each winter from Moorhead to Montana and from Maine to Moscow when soft water turns hard.

So, of course, they wrote a book about it.

A "Hard-Water World: Ice Fishing and Why We Do It" (Minnesota Historical Society Press, 128 pages, $24.95) is a whimsical journey into the world of ice fishing. Kennedy's photos and Breining's short essays illuminate what goes on inside those tiny, dim shacks and outside on those frozen lakes.

"There's lots of 'how-to' books out there, but there really wasn't a book about ice fishing that approached it from the concept that it's part of American culture," said Kennedy, who came up with the idea after collecting a bevy of ice fishing photos from magazine assignments over the years. Two years ago, he set out to fill in the photographic gaps.

"You can't really do just a book on Minnesota, there's too many other people in this boreal forest latitude who ice fish," Kennedy said. So he went from Montana to Maine, and across the border to Canada. "And we have a chapter on Russia."

Kennedy is not an avid ice angler, but he grew up in Alaska, has lived for decades in Minnesota and relishes outdoor assignments.

"I love being out in the winter," he said.

Breining is a Minnesota native, an avid fly fisherman and sporadic ice angler.

"The things I like about fishing -- the rushing water, being able to see down into the water, having the fish race and strike and cavort across the surface, the athleticism of casting -- all pretty much disappears when the ice forms," he said.

But he has ice-fished since he was a kid, appreciates the uniqueness of it and still tries to get out occasionally when he heads to his cabin up north. In researching the book, he was struck by how much winter angling has evolved.

"When I went out with my dad 45 years ago, going ice fishing meant being really cold," Breining said. "You had your leather hunting boots on and as many pairs of socks as you could squeeze in there. Clothes just weren't very good, so you were going to be cold.

"We had an ice chisel -- not even a hand auger. Once you got a hole in the ice, that was it, you weren't going to move, even if you caught sunfish the size of potato chips all day long, because it was too much work.

"Now, of course, you have power augers and great clothes and portable shelters and depth finders -- ice fishermen can be almost as mobile and effective as guys in boats. Gear has really changed the complexion of ice fishing."

So why do people ice fish? The answer can be as elusive as a big crappie.

Breining offered some thoughts:

"It's all kinds of things. Some just really love the winter -- they love the ice, the cold and the snow. Some just really love to fish. Some love to drink beer and have parties. Some just really love to tinker with their houses."

Kennedy said the answer could be simpler.

"I was driving back from up north, and I looked out and saw just one ice house on this lake. There was light on inside and smoke coming out of the chimney. It looked so warm and inviting and peaceful. I think that's one of the reasons people do this. It's a way to get out and do something."

Doug Smith • dsmith@startribune.com