The deaths of two children last week who succumbed after falling into an icy Minnesota lake underscore the dangers of early-season boating and fishing.

"Cold water is a killer,'' said Kim Elverum, Department of Natural Resources boat and water safety coordinator.

Boaters and anglers might be lulled into a false sense of security by the unseasonably warm spring, Elverum said. But water temperatures can still be in the 40s and 50s -- water cold enough to kill.

"The perception is the air is nice and warm, but those deep lakes will take time to warm up,'' he said.

Elverum said water isn't safe until it's around 70 degrees; most pools are at least 80 degrees.

"Cold water will continue to be a problem,'' he said.

It kills at least four ways: Cold water shock, which causes the victim to inhale water and drown; swim failure, because muscles stiffen; hypothermia -- after 30 minutes body core temperature drops, which can lead to unconsciousness and death; and post-immersion collapse, when cold blood trapped in extremities rushes to the heart, leading to heart failure.

The DNR's hypothermia brochure can be viewed at www.startribune.com/a1198.

Muskie Expo

The annual George's Minnesota Muskie Expo is Friday-Sunday at the Gangelhoff Center at Concordia University in St. Paul, and operator Paul Hartman said it will be the largest ever. Some 140 booths will display electronics, trolling motors, rods, reels, nets, lures and muskie fishing destinations. There's also a trout pond and George's Tackle Box, where kids can make their own bucktails, jigs and leaders to take home free.

Seminar speakers include Larry Dahlberg, Luke Ronnestrand, Gregg Thomas and Bob Mehsikomer. Cost is $10; a 3-day pass is $17; children 12 and under are free. For more, see www.mnmuskieexpo.com.

DOUG SMITH