Rivers often inspire philosophizing on the fluidity of life, from the trickle of birth to washed-out death, their strong currents representing the chosen path, the oxbow lakes epitomizing ventures abandoned.

And at other times rivers are just a place to stand in your underwear with a man who's traveling to Argentina.

That's where you were Monday afternoon, the cool water of the Missouri lapping at the stripes on your boxers, your back against the hull of a homemade boat.

It was a little after 2 p.m., and for the second time that day, Kobuk had hung herself up on a sandbar. Rather, of course, it was her pilot who'd misguided her. He'd followed the complete lack of advice from his would-be navigator, who was not at his post but aft, eating grapes under the shade of the canopy and watching a pelican try to catch fish.

For 50 yards in any direction, the water was neck-deep on a dachshund. Experience - including a rather lengthy stoppage in travel just an hour before - told you the best thing to do when marooned on a desert that is covered with water is to have lunch. So you ate sandwiches and grapes, and washed them back with a couple of Heinekens. Pelicans, as it turns out, are jealous creatures. The bird looked at your sandwich and flew away quite haughtily. You put your feet up and watched it go, condensation from the bottle dripping on your pants. You took another drink. It seemed the thing to do.

And then, before the pushing, came reflection.

You were on the river with a man who was traveling to Argentina. From Wyoming. In a boat he built himself.

Cool.

Spike Hampson is a geographer by trade and a philosopher by nature, the kind of man who derives the purest of pleasures from studying the world around him.

For the next year and a half, he will have plenty of opportunity for acute examination.

Hampson has endeavored to pilot his 21-foot runabout from the mountains of Wyoming to Buenos Aires, Argentina - some 15,000 miles away. He will take an illogically circuitous route from here to St. Louis, north to the Great Lakes, east to the Atlantic Ocean, down the East Coast and across the Caribbean to South America.

Hampson's path to the southern hemisphere becomes shrouded in less fuzzy logic the more you get to know the man.

There is a philosophical argument that asks if a man who has, over time, replaced every square inch of his boat, has he not then created an entirely new boat? The point metaphysicians ponder is whether the man is still working on the same boat, or if its nature has completely changed.

In Hampson's case, though, it is simpler to say he is not in the same boat in which he used to be.

A marriage that was unhappy from the start crumbled and, in a phrase a geography professor can appreciate, Hampson's job was cleaved from his life.

He bounced around for a while, working on a sailboat in the South Pacific and taking a job as a ski instructor in Park City, Utah. Hampson found additional part-time employment teaching geography at the University of Utah. Then, he remembered the dream.

He'd always wanted to build a sailboat and travel the world. Once, while living in Hawaii, Hampson built a catamaran. Now, though, living in Utah, a sailboat seemed incongruous with his surroundings.

Then the idea came for Kobuk. Putting the mess of the past few years behind him, Hampson settled into a routine of meticulously crafting a vessel of mahogany and marine plywood that would be equally capable of running in shallow water and relatively turbulent seas.

He built Kobuk - named for an Alaskan river - in four years. He designed her to be different than the place from which he'd come, to be an antidote of sorts to the complications he'd endured. He gave her clean, clear lines and a gauge to tell him just how deep the water was that he was getting into.

Then, he began planning the voyage.

"I'm 61 years old," Hampson said. "I've had this dream all my life, and was finally able to get over the psychological barrier of doing it. That's really the bigger barrier to doing these things. I realized I don't have time any longer to think about doing it, but that I have to actually do it."

Hampson launched Kobuk in Worland, Wyo., in May. He traveled downstream on the Wind River to the Yellowstone, then across Montana to the Missouri. It was all downstream, but not downhill. Hampson lost the channel as the Missouri flowed into Lake Sakakawea and got hung up on submerged trees. He leapt from the boat to push, and landed shoulder-deep in river muck, lucky to still be holding on to the boat. He climbed back in and worked free of the trees after a day and pushed on.

On the other side of Garrison Dam, Hampson found relatively smooth sailing. He motored his jet-drive boat - powered by a 240-horsepower Mazda rotary engine - downriver to Stanton and hit his bunk, a cocoon forward of the cabin and beneath the bow planking.

When he awoke, he stretched, rose and found no water. Kobuk was high and dry, resting on a rocky bed. It is unsettling, being a fish out of water.

By afternoon, the Army Corps of Engineers had increased flow from the dam, and Hampson was able to shove off. He reached Washburn a week ago today.

That is where you joined him, for the trip down to Bismarck.

The voyage was fraught with no peril greater than pushing off of the occasional sandbar, a chore Hampson now performs nearly absentmindedly and without regard to the chilly water. Sandbars can, however, pose a threat to Kobuk's intake system. At one point, she drifted downstream with Hampson beneath her, legs dangling behind under the shallow water. He was removing debris from the intake, a regular hassle and minor flaw in the boat's design.

Otherwise, the journey went smoothly. What lies ahead - traveling in open water on the Great Lakes and across the Caribbean - should prove to be more challenging. If the adventure gets to a point where Hampson can't handle it, or gets bored, he has no qualms about stopping.

"I don't have anything invested in getting to Buenos Aires," Hampson said. "It's just about being satisfied enjoying what I'm doing while I'm on the route. The whole point of the trip is to see the countryside. That's what's important to me."

Hampson expects that - if all goes well in the unprotected waters and he does make it down the Orinoco, Amazon and other waterways to Argentina - the trip will take a year and a half. He'll have to fly back to Salt Lake City every once in a while for brief periods to teach. Otherwise, he will teach classes online, and also will provide a log of his trip at http://www.spikehampson.com.

Life on the slow boat down the river provides plenty of time for reflection. An easy-going but rugged intellectual, Hampson likes to examine various areas of life and compare them to where he is. He enjoys chronicling those thoughts in his log. He's got all the time in the world to get the words right.

"I like not being tied to deadlines," Hampson said. "Is it boring? No. People can say if you've seen one stretch of river, you've seen it all. But it's not like that. Most people spend their lives at a job where everything is the same all the time. Out here, things are different, and not many people experience that."

Hampson enjoys sharing those experiences through his writing, but he prefers solitary travel.

"It's important to me to do as much as possible alone," Hampson said. "I'm not trying to accomplish a record or anything. But I built the boat by myself, with no help. I'm traveling by myself. My friends don't understand it and I can't explain it. The only thing I can say is I'm fulfilling a childhood dream, doing what I was intended to do. It's very self-centered, maybe."

Now, back to pushing.

Hampson, who really, truly, does like to do it all himself, finally needed help. You kicked off your sandals, removed your jeans and hopped overboard. Since he didn't shriek like a little girl when he jumped in, you didn't either. But it was cold.

With two backs against the hull and an extra 230 pounds of weight now removed, Kobuk slid more easily across the bar. Fifteen minutes of wrangling and she was pointed into the channel. For now.

It took about six hours of slow-and-easy traveling to reach Bismarck. There were two kayakers who arrived at the Washburn ramp when you'd shoved off, but they were the only other people you saw on the river until south of Double Ditch.

You got to the Broken Oar, where Kobuk was greeted with appreciative whistles from a few guys, including Jack Gabriel, who knows a cool boat when he sees one. Hampson stayed over in Bismarck two days, lecturing on Tuesday at Bismarck State College.

He's somewhere south now, lost in thought, probably, or knee-deep in the river with his back against the boat. He is in the fast current of his chosen path, no doubt, but you can count on Hampson to poke around the oxbows, too. He's not the type to miss out on an adventure.

(Reach Tony Spilde at 250-8260 or tspilde@ndonline.com.)