Saying that Australians are casual doesn't begin to cover it. They are master artists whose craft is the "no worries" vibe, the same way the French work in pastry, the Swiss work in chocolate and the Japanese work in karaoke.

Which is why it shouldn't have been a surprise to step into the wheelhouse of the Murray Princess and find the captain, kicked back with biker shades on, steering the 950-ton vessel up the twisty, shallow River Murray with his right foot.

Nor should it have been a shock that for our port stop one night, we tied up to a seemingly random tree.

Think "Heart of Darkness" without, well, the darkness.

The Murray is the ultimate lazy river, a 100-million-year-old ribbon of green that winds 1,470 miles through South Australia, Victoria and New South Wales, passing farms, aboriginal homelands, red gum forests, holiday cottages, arid scrub and towering ochre-colored limestone cliffs festooned with snow-white cockatoos. The scenery prompted an American writer in the 1890s to compare it favorably to the mighty Mississippi. (The guy was Samuel Clemens who, it turns out, knew more than a little about rivers and riverboats.)

The river and its surroundings make up a widely overlooked region (except among Aussies) that offers the jaw-dropping, terrible and sun-burnt beauty of Australia, but without the endless drive to Uluru or Darwin that would give a long-haul trucker pause, or the expense of a second or third flight to the Great Barrier Reef.

Traveling by 1800s-style paddlewheel riverboat, the landscape not yet overrun by tourists drifts by so languorously, it seems at times as if the natural wonders of Oz pick up and come to you. A pretty good spot to have no worries.

We left on a Monday from Mannum, a riverside hamlet 51 miles east of Adelaide, for four nights aboard the 120-passenger Murray Princess, operated by Captain Cook Cruises in Sydney. The flat-bottom boat, looking like an Old West boomtown hotel on floats and riding 40 feet out of the water (but just 3 feet below the surface), is perfectly suited for a waterway prone to shallow passes and fickle flows -- even with a system of locks and weirs to regulate it.

Once aboard, we experienced what would be the first of many departures from the typical American cruise of any size: a blessedly brief safety lecture from the captain.

"The river is only about 20 feet deep. If the boat is actually sinking, just come up to the top deck and you'll stay out of the water," he said, drawing hearty guffaws among the mostly Aussie crowd. I caught a few Americans laughing nervously and looking outside to gauge the distance to shore.

Rugged on the outside

The rugged landscape outside the windows does not carry over onto the boat, where the cabins are comfortable and clean (and light on the usual "luxury" frills), and the lounge is stocked with stuffed leather chairs and a picture-window view of the paddlewheel in action. The elegant dining room is also far from rustic: Meals on white linen were Australian takes on British and French favorites.

At our table the first night, the seven of us -- two Aussie couples, a scholarly British woman traveling solo and a pair of Americans (us) -- discussed language and the many liberal interpretations of the word "English," haggled over selective use of the metric system and thoroughly hashed over, of course, U.S. politics (just three weeks before the November election).

In the morning, I snuck upstairs to find mirror-perfect water, not yet disturbed by our paddle or the multitude of pelicans we saw the night before. The serenity was shared by the still lavender sky and air devoid of even chirping as I waited for something or someone to put the first ripples of the day into the glassy Murray.

A river like the Mississippi

In large part, the Murray does resemble the Mississippi River -- not so much today's water highway choked with oil tankers and container barges, but the Mississippi of Huck Finn's day. I stood at the railing for an hour after breakfast, surveying what counts for traffic here: excursion boats, fishing skiffs, secure-line ferries, a couple of smaller paddlewheelers and a funky armada of houseboats, ranging from yachtlike to shack-caught-in-a-flood. (The ferries make up for the 100 miles of river with no bridges.)

On the Princess, days (in between the meals) are a mix of lectures on river history, trivia games and free time to chat, drink or become mesmerized gazing at the bizarre tangle of river red gums along the banks, the ubiquitous mallee trees atop the cliffs and weeping willows draped into the water like frozen green waterfalls.

Trips ashore also break up the day, including a tour and tasting at Burk Salter winery near Blanchetown and a guided stroll around the settlement of Swan Reach, whose near destruction in the flood of 1956 is well-documented in the town's friendly, funky museum.

In Sunnydale, we toured the Native Wildlife Shelter, essentially a petting zoo for Outback outcasts, with displaced or recovering wombats, kangaroos and a pair of alpacas (probably couch surfing until they get enough traveling money to get back to Peru).

By far the most colorful (and possibly most disturbing) slice of River Murray culture was the woolshed show next door to the shelter that included a sheep-shearing demonstration, a lecture on blow-fly strike (don't ask) and a pageant of sheep dressed in panties, bras and boxers, some with dyed Mohawks.

That night, we moved ashore for a barbecue picnic that included a bonfire, singing, grilled kangaroo and immersion into the local culture through an ancient ritual dance called "The Hokey Pokey." (Participation was high, if only because the crew's makeshift bar was doing a brisk business.)

Following the meal, we rode in tractor carts through the darkness, spotting kangaroos and wombats in the wild, as well as the glowing, beady red eyes of trapdoor spiders reflecting our lamp light.

The last full day of the trip was divided between relaxing and visiting Ngaut Ngaut Conservation Park, an aboriginal site of the Ngarrindjeri and Nganguraku people where archaeologists are studying rock carvings dating back a few thousand years. The guides talked about the importance of the land, explained the fascinating and baffling rock art and, when necessary, shooed away prehistoric-looking emus as if they were pigeons.

The rest of the day was spent lazing on the top deck with tablemates Monika and Pete, who live near Melbourne, laughing over a Lonely Planet guide to speaking Australian and the several hundred colorful ways to say that someone is drunk. Mostly I just gazed at the limestone cliffs, viewing some stretches as impenetrable castle walls, others as long-vacated ruins and yet others as melting layers, like a mud-brick home in a monsoon.

A 'no worries' state of mind

Big Bend, the most imposing stretch of cliffs, is aptly named. While the curve in the waterway itself is not particularly extreme, the "Big" probably refers to the particularly impressive cliffs that, in the afternoon sun, form a burnt-orange stripe between the murky green and cobalt blue stripes of the water and sky, like the curious new flag of a breakaway republic.

Throughout the walls, the Swiss-cheese holes are castles to sulfur-crested cockatoos, an exotic bird that's a little too common for vineyard owners (they eat the grapes) and whose blood-curdling screech is amplified threefold by the limestone sounding board. I tried yelling back at a few, but somehow the words "No worries" were on a loop in my head, and I sat back down and took another swig of my West End Draught.

Except for the barely noticeable vibro massage from the engines, the paddlewheeler glided so easily that it seemd entirely possible the fossilized cliffs were moving left to right -- like a backdrop of Monument Valley scrolling behind the hero in a 1930s western -- and that we were the stationary objects.

Blissfully slouching in the chair, shades on, I propped my feet up on the railing. I couldn't help but wonder: Any chance the captain would let me drive a while?