When an ice climber approaches a wall, he enters a conversation. It starts with a swing of his axe.

The ice replies with a “thunk” or “shunk” or “crunch.”

And the climber responds by either putting his weight on the ax; taking another swing; or walking away from the wall altogether, saving the conversation for another day.

“There’s this amazing, indescribable series of tones for different types of ice,” said Ian Kirk, 30, of Bar Harbor. “The sounds you hear are not only awesome, but they also can tell you a lot about how the ice is reacting to your swings, about whether your tool is good to go or sketchy.”

An ice climber’s safety hinges upon understanding the language of ice, among other things. Misinterpreting one sound could result in disaster — potentially injury or even death.

“It takes years to learn what ice is capable of,” said Luke Cushman, 32, of Old Town. “And that’s what you’re climbing, that’s what’s keeping you from falling.”

Kirk and Cushman have been ice climbing together since they met at the University of Maine in Orono several years ago. They also climb with and Charles “Chuck” Drew, 27, of Portland, and Jeremy Robichaud, 34, of Orrington.

“Having good partners that you can trust implicitly — and also put up with — is key in ice climbing,” Cushman said. “It can be a very miserable activity at times, and having someone who is there that you know will take care of you is important.

From Grafton Notch to Camden Hills to Acadia National Park, the group has sought out ice routes together.

Last winter, the four men packed their climbing gear — crampons and carabiners, ice screws and axes, harnesses and helmets, food and clothing — and cross-country skied 17 miles into Baxter State Park to set up basecamp at the Chimney Pond bunkhouse. They then spent the next few days climbing remote ice walls on Katahdin’s steep slopes.

“You’re going to slog through a bunch of deep snow; and you’re going to be cold for a big part of the day; you’re going to shiver and curse and it’s scary,” Kirk said. “There’s a bunch of things you have to recognize you have to go through before you swing your first tool.”

“I think the most challenging part of ice climbing is dealing with the weather and the cold,” Cushman said. “You’re always looking for new gloves and thicker socks and trying to figure out how to tie your boots without cutting off the blood flow.”

Yet they’re addicted to the sport.

“It’s Type II fun,” explained Kirk. “Type I fun is: ‘Wow, this is a blast,’ when you’re doing it. And type II fun is not really fun at all, and then you look back on it and think, ‘Wow, that was really fun.’”

“It’s worth it because it’s risky and can be scary and can be uncomfortable and even painful,” Robichaud said. “Those are the experiences that are worthwhile. If it was easy and comfortable, then anyone could do it. We would have Sandals Resorts at all of our climbing spots.”

While ice climbing and rock climbing seem similar, there are some major differences — differences that deter many rock climbers from ever approaching an ice wall.

“You have to go into ice climbing with a different mentality than when you go into rock climbing,” Robichaud explained. “Back in the 30s and 40s, when rock climbing came into its own, there was a mentality that the leader never falls. And over the years, that has changed. We’ve had advances in equipment, and now it’s completely the opposite; the leader is a person who’s most bold and willing to take big falls.”

Rock climbers describe falls using some basic jargon:  A “screamer” is a fall long enough to provide the climber the luxury of vocal panic. A “whipper” is similar to a screamer but pulls the vocal routine back to normal as the rope catches the climber and saves them from falling. A “crater” ends when the climber hits the ground.

“Every rock climber has their story of their big whipper or fall,” Robichaud said. “It’s expected now with rock climbing.”

“But with ice climbing,” he continued. “There’s still that mentality that when you’re leading, you don’t plan on falling, and that’s for a lot of reasons. There’s a lot more risk associated with falling because ice isn’t as reliable as rock as far as protecting you. It’s always melting and changing. Ice breaks and falls on people. Conditions vary. And we have sharp, pointy things all over us.

Cushman’s brother, Matt, was ice climbing in Ouray, Colo., when he fell. The metal spikes of his crampon caught a quickdraw (a piece of equipment attached to an anchored ice screw) and his ankle shattered.

Even the “easy” ice routes have the potential to be dangerous, Cushman cautioned. It only takes one moment of inattention to slip up, quite literally.

“Every single step and movement is critical,” he said. “If you fall upside down on ice that’s just at a 20- or 30-degree angle, you can accelerate to 60 mph in seconds. It can get scary fast.

Peter Lataille, 51, of Hampden, was climbing “Remission,” an ice route on New Hampshire’s Cathedral Ledge, when the column of ice he was climbing suddenly let go. He fell 60 feet before a piece of gear caught him. He was dangling just 8 feet above a ledge.

“I stopped ice climbing for a few years,” said Lataille, who started climbing in 1980. “I didn’t trust ice anymore.”

But he didn’t stay away for long. His love of the sport trumped his fear of it, and he picked his axe up again.

“You’re always climbing around incredible sculpture,” said Lataille. “The ice is just gorgeous.”

Unlike rock climbing routes, which are relatively unchanged from week to week, ice routes are constantly morphing as they melt and freeze.

“You can climb the same route all winter long and not have the same experience,” Kirk said. “That’s what makes it so cool.”

Nevertheless, ice climbers can get a general idea of an ice route’s difficulty by looking up its rating in a guide book, such as “An Ice Climber’s Guide to Northern New England,” by Rick Wilcox, or on websites such as neclimbs.com.

While climbers use a number of rating systems, depending on where you are in the world, most New England routes are rated on a commitment scale of Roman numeral I to VII and a WI (Water Ice) technical difficulty scale of 1 to 5+.

Ice routes often sport clever and amusing names, reflecting the high spirits of the men and women who first conquered them. For example, “Piggy Wiggy” — a II3 route on the South Basin Headwall of Katahdin — is named after the first ascent party’s stuffed animal mascot. The I3+ “Yellow Mustard Custard” climbs a runnel of yellow ice that extends down a cliff in Grafton Notch.

While many ice climbers are self-taught or learn from friends, Cushman suggests people take lessons from professional guides, people who are trained to impart the nuances of the sport. For example, Acadia Mountain Guides offers ice climbing lessons at a variety of skill levels.

“I think it’s worth trying for everyone,” Robichaud said. “But it shouldn’t be taken lightly. It’s serious and it’s risky. If you’re going to go out, make sure that whoever’s going out with you knows their stuff.”

And if conditions aren’t right, be prepared to walk away from the wall.

Cushman and Drew skied across Moosehead Lake to the base of Mount Kineo three times before attempting the famous “Mainline,” a III5+ route up the face of Mount Kineo. The first two times, the pair decided the ice wasn’t safe, and they walked away from the wall. But on the third trip, they climbed to the top without incident.

“Last winter, I felt like I climbed a lot, but almost half the time, I was backing away from stuff just because it didn’t feel right, conditions were bad,” said Cushman. “But that’s the thing. You can climb tomorrow. If you do it and something goes wrong, you can’t climb tomorrow.”

Aislinn Sarnacki

Aislinn Sarnacki is a Maine outdoors writer and the author of three Maine hiking guidebooks including “Family Friendly Hikes in Maine.” Find her on Twitter and Facebook @1minhikegirl. You can also...