They boldly go where you shouldn't be in the first place.

Casper Fire-EMS personnel stood around a tree on the bank of the North Platte River on Thursday afternoon to learn some of the finer points about the equipment used for ice rescues.

"It's a very dangerous activity for us today," engineer Tye Herron said after the training.

Earlier, he showed about 20 fellow firefighters how to secure a "wrap 3, pull 2 anchor" around a tree and rig a "tandem prusik belay system" for a lifeline connecting a raft, when to use the equipment, and what to decide before venturing on the ice to rescue someone while staying safe themselves.

After that lesson, two firefighters finished donning their waterproof ice rescue suits. Others helped them with life preservers, and hooked straps to rings on their back and then to rings on the "banana boat," nicknamed for its color and shape.

Because the bow and stern of the raft are open, firefighters can stand in the openings, grab the sides and walk on the ice. The raft is capable of transporting up to six people.

The training was for all the crews in the Casper Fire-EMS Department, Herron said. "The whole city's going to be on the same page."

The ice on the river near the First Street Bridge was about five inches thick. Herron wished it might have been a bit thinner for more of a challenge, but it still is dangerous work, he said.

And if it's dangerous for them, it sure is for you.

River rescues in good weather are bad enough. River currents do not flow consistently forward. Water may flow faster or slower underneath the surface, and there are undertows.

Those conditions and more are worse in the winter when ice and current come together, Casper Fire-EMS spokesman Pat McJunkin said.

There's no such thing as safe ice where it comes to moving water, McJunkin said. "Rivers, streams, anything of that nature where there's current, where water's moving beneath the ice -- there's no way to know or determine whether the ice is actually safe to be out on."

When someone falls through the ice, the situation becomes that much more dangerous, he said. "It takes a great deal of effort to try to self-rescue in that type of a situation."

The current pulls on the body, and the cold water rapidly depletes the body's energy as the person tries to stay on the ice, and hypothermia sets in quickly, McJunkin said.

"Most people just aren't going to last in that situation for very long," he said.