Summertimes in the mountains around Charlemont used to be peaceful for the birds.

Located on the Deerfield River and nestled halfway between Greenfield and North Adams, Charlemont’s year-round bird population knew if they wanted their birdcalls heard in the winter, they could expect a good deal of noise interference from skiers on the slopes of Berkshire East hooting and hollering. During the spring, summer and fall, our feathered friends also knew that if they were looking for tranquility, free of human exclamations of exhilaration and joy, they’d steer clear of the river, where outfitters like Zoar Outdoor conduct whitewater rafting, kayaking and canoeing tours.

Fair enough. But as soon as the snow melted and the chairlifts ground to a halt, the mountains were theirs.

In recent summers, though, even the birds’ mountain airspace has been rudely invaded on occasion. Throughout the forest canopies on both sides of the river, the sweet sound of summer birdsong is often now pierced with the periodic hoarse cry of “Holy fucking shit!”

And dangling from a hot metal cable, a wingless human carcass will fly through the branches once reserved exclusively for the fauna—a blurred streak of color, moving at times faster than the cars in the area are allowed to drive. Sometimes even twice as fast.

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In the past two years, both Zoar Outdoor and Berkshire East have added zip line canopy tours to their roster of outdoor activities.

Thick spans of high-tension metal cable have been stretched through the forests and mountains around Charlemont. Unlike power lines, these cables have been strung not to find the shortest route between two points, but to offer the best rides for the paying visitors. Like inverted squirrels, thrill seekers ride zip lines suspended in a climbing harness hooked onto a hand-sized metal trolley that rolls along the high-tension cable.

The beginning and end points for each zip line are carefully chosen—as you descend the cable, you accelerate, but as the cable climbs to the landing point, you slow down. Some rides are good for viewing the mountaintop vistas and treescapes, and some are good for speeding through the woods and feeling the wind in your teeth. Some zip lines only go a few hundred yards, close to the ground. Others go nearly half a mile at groin-shrinking heights.

Both the Zoar and Berkshire East canopy tours offer breathless adventure in the treetops with friendly, safety-conscious guides. Still, they are strikingly different experiences, each with much to recommend it.

This reporter took on the assignment of evaluating both zip line tours. For an additional perspective, the reporter’s brother agreed to sacrifice some work time in the interest of journalistic integrity.

We began our investigation at Zoar Outdoor in mid-May on a perfect, clear day when the foliage had just begun to fill in. As you head west along the Mohawk Trail from the Connecticut River, Zoar is on the far side of Charlemont on the right side of the river. Its canopy tour descends from the summit of Hawk Mountain back to its base of operations near the road. The three-hour trip costs $85 per person.

Our guide, Nina Nunes, recognized me from a visit made over a year ago, before the tours were up and running, and she quickly got us in our gear, explaining what everything did. Accompanying us were two other zip guides, Tim and Zakes, local guys recently back from college for the summer, reacquainting themselves with the route and its improvements since last year. Our names were all written on masking tape and affixed to our helmets. Everyone was warm, relaxed and funny; the guides demanded your attention and caution, but they never forgot that this was supposed to be fun.

Before we started, each of us hooked on to a practice zip line to learn the fundamentals.

Zoar’s zip lines are doubled, meaning that each trip you make is along two lines running parallel, one above the other. A metal trolley has wheels that run between the wires. Wearing thick leather gloves, zip riders at Zoar hold on to the top of the trolley during their ride, and as they approach their landing spot, a guide flaps his or her arms to let riders know when they should apply their brake. Braking is accomplished by placing your thick glove behind the trolley and pressing down on the cable you’re speeding along to produce friction (and considerable heat). The guides have additional equipment to help slow zip riders down before they crash into a tree and/or a guide, but rider focus and cooperation are definitely required. In the event that someone brakes prematurely, we were also trained in self-rescue and how to crawl along the line if necessary. We were told this inelegant maneuver was only once ever employed in Zoar’s two years of business.

Once we were comfortable with what we had to do, the group piled into a four-by-four and drove the rugged, steep track to the top of the mountain for the first takeoff platform.

Though the trail we took was muddy, rugged and torn up, the rest of the forest seemed more or less intact despite the recent, dramatic construction needed for the zip line tour. While a lot of trees had clearly been cut to clear the paths, even while zipping, you still often had a canopy above you. Nina and others have emphasized that they planned their course to preserve as much of the growth as possible and to strategically feature particularly impressive trees.

The Zoar canopy tour starts near the top of the mountain, working its way down in stages, with zip rides getting increasingly longer, faster and more dramatic.

At first, the not-so-distant landing platform was visible from our launching point. Nina reviewed the basics one more time before heading off herself. She made it look effortless. She leaned back in her harness, feet locked together and pointed forward, finally swooping onto the distant platform and getting ready to receive the rest of the group. The other guides helped hook our trolleys onto the zip cables one at a time, always making certain we were connected to at least one anchor—usually two—at all times. When we were ready, the guides called out back and forth to alert everyone and prepare for the eminent delivery of a human being into the open arms of gravity and speed.

For much of the tour, even while standing still, you’re aloft. Several stretches of the tour go between crows’ nests high in the limbs. Some launch pads are reached only after spanning rope bridges. Twice you return to the ground by rappelling from your lofty perch. The best wide views of the valley happen early in the Zoar tour from one such platform: hanging out crazy high up in the trees, waiting for your turn to zip, it’s a joy to watch birds fly and land beneath your feet. And then, before you know it, you’re whizzing through the same air, watching the ground fly under you.

Later in the Zoar course, the cables dip down beneath the forest canopy, and from your launch pad, it’s impossible to see where they’re heading. It’s equal parts unnerving and thrilling having no idea where you’ll land, and by the time you find out, you’re going too fast to turn back. While everyone else on the tour was able to achieve superhero-worthy landings, I seldom managed anything close. More often it felt like a controlled collision. Nina was patient and prepared for when I came “in hot.” After being initially a little frustrated, I gave up worrying overmuch about how I looked and enjoyed the speed my particular body type achieves (read: XXL). During the final and longest stretch of the Zoar tour, I was told some people approached 30 miles per hour.

My brother and I went home delighted, feeling our expectations exceeded.

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Last week, my brother and I returned to Charlemont, this time turning left at the bridge and heading up to the mountain where the winter’s ski slopes were now windswept fields. Whereas Zoar’s zip line courses have a delicate touch, Berkshire East’s zip lines are clearly hewn by people who understand the lure and importance of speed and long, uninterrupted runs.

They offer three separate tours. Thirty dollars buys a run between platforms that span the vast open space where various slopes meet just outside the lodge. For $85, visitors can take the chair lift to the summit for the Mountain Top Tour, which follows a course of moderately challenging zips between slopes around the mountain. We went on the $110 Valley Jumping Tour, which mingles with parts of the moderate tour, but starts out fast and ends with speeds that make you tremble for minutes after landing.

We geared up in the lodge with guides Mark Bennett and Emma Olson and took the chairlift up the mountain. At the top, Emma gave us a brief review of the equipment, but as Berkshire East’s system doesn’t require zip riders to brake themselves, there’s less to discuss and review. It appeared that Berkshire East’s zip cables were strung with more slack, so that while riders achieved higher speeds more quickly, there was more of a climb at the end to compensate. While there were some tall wooden launching platforms, the majority of the zip lines landed on the sloped ground, and combined with the braking techniques employed by the guides, landings didn’t need to be as precise.

Which was a good thing for me. The very first zip line we tried seemed longer and faster than anything we’d tried at Zoar. While by holding on to the trolley at Zoar I’d usually been able to keep myself pointed in the right direction, at Berkshire East you’re not wearing gloves, and you hold the tether binding you, keeping your hands away from the wire.

More often than not, I found myself spinning gently in space, kicking spastically in the air, trying to right myself. We were shown how to steer by holding the clip above the tether, but we were also advised that you could miss all there is to see by worrying too much about which direction you were going in. Steering also slowed you down. After the first couple of zip rides, I settled into enjoying hurtling through the forests, not minding that my undignified landings seemed to amuse some of my companions.

The forests on Berkshire East have been less well cleaned up than Zoar’s since the zip lines were installed. Many were clear-cut through everything between the two points, leaving an ugly tear in the canopy. Instead of working your way down a single mountain, you have a lot more walking to do between zip lines at Berkshire East, and whereas some walks can be beautiful, there’s also a lot of construction on the mountain (including preparations to install a windmill). Often we were trudging through muddy tractor ruts or zipping over the graveyards of trees left to rot where they fell.

Not that any of that mattered a whole lot at high speed. As we zipped our way through the tour, we were lured forward by the promises that we hadn’t seen anything yet. And we hadn’t.

Stepping from the woods and first seeing the Herculean span of extreme zip line stretching to the distant hilltop felt like an Indiana Jones moment, and even before I’d stepped on the small launching platform to get latched on to the cable, I found myself grinning and muttering obscenities. Someone in a red Berkshire East jersey lolled around on the distant hilltop waiting for one of our instructors to head over; he was a barely discernible speck on a massive arm of mountain. When the first guide headed over, we all listened to the whirring hum of the cable as he flew along for nearly half a minute until he joined the distant speck.

If the giant leap across the valley weren’t enough, they’ve installed tandem lines here, allowing for pairs to zip together. My brother and I launched into the space far over the valley together, he a few steps ahead as usual, but as we picked up speed we began shouting, maintaining eye contact, and I slowly passed him. Even with all my flailing, my superior girth helped me win the day.

Adrenaline made me feel weakkneed when we landed, and it was difficult to say anything sensible for a while. When we all were down from our rush, Emma reminded us of what had been made clear at the base camp, but now sounded ominous. To get back to the home mountain we just left, we had to go on one last hike to the final zip line, and the hike would be about 10 minutes long and straight uphill.

She did not lie, but the guides handed out water bottles, and everyone was patient when a couple rest stops were requested. Also as promised, the arduous but beautiful final hike was well worth it.

The final zip on Berkshire East’s valley hop is longer and descends further than the first impressive trans-valley leap, and it’s also strung to be a tandem. Emma said she’d timed herself on this zip at 65 miles per hour, and I was advised to “go starfish” as I approached the landing, spreading my arms and legs out to help slow me down a bit.

We needed to run down the hillside a short way before allowing the harnesses to take our weight, but the slope of the hill was sharper here, and we were quickly far above the forest, looking down at the dirt road that ran along the valley bottom. I felt like Peter Pan, marveling at the panorama I was traveling through so speedily that the air whistled through the holes in my helmet. But then I began to spin helplessly in space again, and my glimpse of the Never Never faded. Instead of going starfish on landing, I went more like mosquito on windshield. All the way home, though, my brother and I were in agreement that the final ride of our zip tour exploration was a touch of something sublime.

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I was assured by both Zoar and Berkshire East zip line guides that they never got over the thrill of taking their courses, no matter how many tours they led. And I believed them, but they were unable to compare the two trips for me. While they were curious about the other company across the river also offering zip line tours, none of the guides I spoke to had yet ventured into the enemy camp. I think, like my brother and me, when they finally scout the competitor’s zip lines, they’ll find there are features of their own tours which are unique, and that each camp can be proud.

If they were movies, I’d say Zoar Outdoor offers a slightly more dignified swashbuckling experience, like Errol Flynn’s Robin Hood hanging out in Sherwood Forest. The built environment of lofty tree landings, as well as the apparent care given to keeping the mountain feeling wild, makes for a more focused zipping experience. Berkshire East is more along the lines of a modern action thriller. While there’s more time between adventures, the action has a harder edge with more spectacular payoffs. It’s more physically demanding and exhausting: think Bruce Willis or Daniel Craig.

Later this summer, my wife and I are going to head over to Zoar’s zip lines for her birthday. If a stack of cash falls in my lap, I’d love to hurtle through skies above the Berkshires in the fall, screaming vulgar words at the birds that nest there.