SCREAM …

That’s the word that dominates the home page of Kohala Zipline’s website.

“It’s what you naturally feel like doing when you’re zipping,” said Mike Pickard, the company’s operations manager. “You’re screaming because you have this rush of adrenaline. You’re screaming simply because you can; you’re out in the wilderness and don’t have to worry about disturbing anyone. And, yeah, you’re screaming because you’ve taken a big step out of your comfort zone and are thinking, I can’t believe I’m doing this!”

Pickard should know. When he first started training as a Kohala Zipline guide more than four years ago, he had many sleepless nights. “I was extremely nervous and didn’t want to continue,” he recalled. “The training was mentally and physically stressful. It pushed me to my limits. I talked to Rob Pacheco, Kohala Zipline’s owner, and he told me to stick it out.”

Slowly, Pickard gained confidence as he went through the 60-hour certification course. “I developed qualities such as leadership, assertiveness and determination that will serve me for the rest of my life,” he said. “I learned that sometimes the hardest things you do can wind up being the most rewarding.”

Today, Pickard zips with ease and counts himself lucky to oversee operations for Kohala Zipline’s two tours on the slopes of extinct Kohala volcano. They’re billed as “aerial trekking” — a cool description for gliding along nine “tree-to-tree” zip lines, crossing five suspension bridges up to 100 feet above the ground and rappelling 40 feet in a pristine, privately owned forest that’s not otherwise open to the public.

“Tree to tree” means the zip lines’ platforms are built into the trees; participants spend the majority of the tour time in the canopy. They aren’t walking up and down stairs to get from platform to platform; they’re flying between them at speeds of up to 45 miles per hour.

The three-hour Kohala Canopy Adventure begins with a 20-minute ride to the course from Kohala Zipline’s headquarters in Hawi. After leaving Akoni Pule Highway, the route climbs mauka (toward the mountains), passing macadamia nut orchards and ranch lands with panoramic ocean views. The six-wheel-drive Pinzgauer traverses an unpaved trail there, so be prepared for quite a few bumps and quite a bit of mud if it’s raining.

First up on the course is a 110-foot practice run, during which the group learns how to control their position, speed and braking and properly “sit” in their harness for optimum balance and security. As they move through the course, they encounter progressively longer and faster lines (height is an additional thrill on Line 5, which rises 12 stories from the forest floor).

Measuring 1,100 feet, the dual, side-by-side final line stretches over a portion of the Kohala Ditch, a 23-mile irrigation system that opened in 1906 to supply water to several sugar plantations that formerly surrounded the towns of Hawi and Kapaau.

“You’ll see the forest from a bird’s-eye view,” Pickard said. “There are gingers, hapuu and uluhe ferns and all kinds of trees, including guava, kukui, ironwood, cinnamon and eucalyptus. If you look carefully, you can see remnants of taro patches that probably date back centuries.”

The course was designed to have minimal impact on the environment. Before construction began, arborists examined dozens of trees and recommended the ones that would be best to anchor the cables and platforms (they check the health of those trees annually). All components — including lines, bridges and platforms — were installed in a way that doesn’t hinder the trees’ growth.

Kohala Zipline is a member of the Association for Challenge Course Technology (ACCT), the zip line industry’s governing body, and meets or exceeds all of its rigorous standards for construction, operations and training. Multiple redundant safety systems are in place, including double aircraft-grade galvanized steel cables with durable WhisperLine nylon coating, which reduces the sound of gliding by more than 50 percent.

“The oldest guest we’ve had was a 97-year-old man,” Pickard said. “He did the first two lines; zipping was something he wanted to check off his bucket list. Every day, we have guests who want to zip but are afraid of heights. We coach them and encourage them, and they have a big smile on their face when they complete the course. It’s great to see someone go from being scared and unsure to excited and happy about their once-in-a-lifetime adventure in just a few hours.”

Notes: Kohala Zipline also offers the Kohala Zip & Dip, which includes everything on the Kohala Canopy Adventure plus a short hike (there are seven waterfalls along the way) and swimming in a waterfall-fed pool. Cost is $249 per person, $209 for kids. The same kamaaina rates apply.

Participants must be at least 8 years old, weigh between 70 and 270 pounds and be able to walk over uneven terrain and up about 25 stairs on their own. They should be in relatively good health, with no existing or previous injuries that could be aggravated by moderate physical activity.

The tours are not suitable for pregnant women and those with back or neck problems, an extreme fear of heights and/or a condition that would require immediate medical attention (e.g., asthma, insulin dependency, severe allergies or heart disease).

Wear comfortable clothing (tops with sleeves and pants, capris or knee-length shorts are recommended) and sturdy, closed-toe walking shoes. Flip-flops, sandals, Croc-like shoes and water shoes such as Tevas are not allowed. Bring a hat, sunscreen and a light jacket or sweater.

Cheryl Chee Tsutsumi is a Honolulu-based freelance writer whose travel features for the Star-Advertiser have won several Society of American Travel Writers awards.