Thirty metres above the ground, I was beginning to regret my earlier bravado.
A cold sweat covered my body and my hands were shaking involuntarily. Every time my rope lurched back slightly, so did my stomach. I didn't want to look down but, when I did, I noticed my rental car was becoming just a grey speck on the ground.
This, I guessed, was vertigo.
"Hey Mike, how ya doing - you're pretty quiet over there," said my instructor, Rob, as he swung around from the other side of the tree. I smiled an "okay", and refocused on scaling this natural skyscraper.
It was taking child's play to new heights. In central Oregon, in the middle of the legendary forests of the Pacific Northwest, I was attempting to climb a 76m Douglas Fir tree.
Oregon is the perfect place for such extreme adventures. Almost half of Oregon is forested and this was old growth forest, untouched by logging.
Earlier, my instructor Rob Miron - whose mother started the Pacific Tree Climbing Institute at the age of 50 - had assured me that it is "tricky" for the first "30 feet or so" and then you find your climbing rhythm.
I put on an extra jacket ("it can get cold way up there") and was hooked on to the ropes as Rob explained the technique.
When I had been offered the opportunity a few weeks earlier I was torn. Thrilled by the adventure, but my stomach twisted in knots as I read about the heights. Eventually I decided to "go for it".
I had done some occasional rock climbs of around 10m but unlike rocks, which tend to vary in gradients, trees are completely vertical. Up, and more up.
As I began, I sat back in my harness, trying to relax, as my feet adjusted to being in the stirrups. Climbing was a two-step process. First, as you held the rope with your right hand, you released the bottom ascender and slid it up the rope, as you lifted your feet into your stomach. Then you stood up in your harness, pushing the upper ascender skyward.
It was inch by inch, foot by foot, metre by metre.
On the other side of the tree I caught glimpses of Nancy, a Californian on an "adventure holiday" in Oregon. Rob and assistant guide Sarah - who had discovered a love of the outdoors during a spell at Lincoln University ("I'm from a small town; my parents think I am crazy climbing trees and abseiling down rocks") - moved between us both, offering steady words of encouragement.
About halfway up, I was discovering new limits to imaginary fears. "Just don't look down" I kept telling myself, not easy when you needed to glance downwards to move your feet up the tree.
I fixed on the horizon, taking in the spectacular sights as we rose above the initial canopy. I was completely safe - held by three separate mechanisms that had been tested at more than 1500kg - but your mind does play tricks 20 storeys off the ground.
Oregon has more hot springs than any other US state.
Still, it was an incredible place to be and I began to enjoy the experience. In silence you could only hear the sound of the birds and the shuffling of leaves. As we climbed, Rob regaled us with stories and told us about the history of the forest.
About two-thirds of the way to the top we reached the first branches - it was nice to put your feet on a limb for a moment. My shoulders and arms were beginning to tire and my hands ached as I tightly gripped the rope for all it was worth.
The object of our quest was within reach - a "treeboat" sitting among the top layer of branches, metres from the top.
Nancy was first into the a treeboat - essentially a wider and flatter version of a hammock. I took some photos for her - all I could think about was not dropping her iPhone - and a few minutes later I was relaxing, as much as was possible, in my own treeboat, more than 70m off the ground.
I ate lunch and sipped on water as my eyes took in the surroundings. The autumnal forest stretched on forever as curious birds fluttered close by.
What an experience. It was an incredible activity; offering a combination of pure adrenalin and a zen-like experience, extreme as well as serene. Returning to earth was a breeze as I let myself down at my own pace. Gazing back at the tree as we said our goodbyes, there was also the satisfaction (unlike some other adventure activities) of true accomplishment.
Sandboarding was another Oregon activity. Like the Far North of New Zealand, the southwest coast of Oregon offers an extensive range of dunes.
"If you can stay on the board there is really no limit to how fast you could go," said Lan Beale, as he explained the fundamentals of boarding on the grains, "just make sure you close your mouth if you crash".
Beale was one of the pioneers of sandboarding, experimenting with a cut-down water ski in the early 1970s and he opened the world's first dedicated sandboard park in 2000. The shop inside features jars of sand from runs around the world (from Egypt to Peru); outside are two ramps and 16.18ha of private dunes.
First impressions - it's a real buzz.
It's not as fast, but easier (the board doesn't start to slide away as you stand up) and less painful (the sand is more forgiving than snow and ice) than snowboarding. Wax is applied to your board after each run and it's good exercise, as you slog your way back to the top of each dune.
Sunset in Portland is an arresting sight.
Oregon: adventures abound
Oregon is one of the adventure capitals of the USA. There are 13 commercial ski areas (around 400 trails) across three mountain ranges. The state also boasts the the largest network of scenic cycle ways in the country and there are stunningly scenic hikes. The abundant forests also provide endless mountain-biking options.
You can also visit the deepest lake in the world, or wander alongside the deepest carved river gorge.
The 584km of coastline has renowned surfing, kite-boarding and windsurfing spots and the river network offers kayaking and rafting thrills. For a touch of the wild west, you can join a high desert horseback ride or cattle drive, and stay at a dude ranch. If all that's not enough, there's even 17 ghost towns to explore.
IF YOU GO
Getting there: Hawaiian Airlines flies three times a week from Auckland to Honolulu. From Honolulu, Hawaiian Airlines connects to 11 US mainland destinations (including Portland, Oregon) and has a 2 x 32kg bag allowance. Phone: (09) 977 2227.
Michael Burgess flew to Oregon courtesy of Hawaiian Airlines and was hosted by Travel Oregon.