Traffic has come to a halt. Onlookers are craning to spot something by the pine forest, a canopy of thinning conifers and wind-battered branches.
My husband deftly steers our car onto the road shoulder. I alight to investigate, soon to realise that this is foolhardy.
"Bear," a voice thunders.
Feverishly, I bolt back into the car and seal the doors. On our right, through the thicket, is a riveting sight. I see the round prominent ears first. The beady eyes squint in our direction for a moment before the bear turns its snout to an ample harvest of whitebark pine seeds.
The black bear - a misnomer, really, for its coarse coat is dark brown - is foraging and feasting, with a cub grazing beside it, barely 4m from our car.
It is both thrilling and daunting, considering that park regulations stipulate that visitors, when on foot, should keep a distance of about 90mfrom bears.
In the cocoon of our car, we gaze silently as the bears chomp on their pine nuts, unperturbed by, or perhaps habituated to, visitors.
Instinctively, I raise the camera. Awed by my surreal proximity to the wild animals, I shoot away intently.
At the Yellowstone and Grand Teton National Parks in Wyoming, connected to each other via a short 12km drive on the John D. Rockefeller, Jr Memorial Parkway, it is not too difficult to take decent photographs because the sights are so intriguing, including some that surprise us, such as the bear.
In Yellowstone, herds of wildlife roam the grounds, coexisting with a cache of remarkable geothermal features concentrated in one spot.
Not to be outshone, Grand Teton boasts views of saw-toothed peaks that rise dramatically from the valley floor.
We are here for a photographic expedition and are about to be deeply humbled by the pristine landscapes, ethereal thermal wonders and awe-inspiring wildlife.
Yellowstone is a biosphere reserve that is home to more than half of the world's geothermal features, with more than 10,000 hot springs, mud pots and geysers of sublime colours and forms.
The most memorable for us is the Grand Prismatic Spring, what I consider to be nature's magnum opus in Yellowstone. Measuring 112m wide in Midway Geyser Basin, it is a dazzling kaleidoscope of orange, yellow, green and inviting blues.
The stunning colours are produced by thermophiles, or bacteria that thrive in extremely hot mineral-rich waters. Species of different colours live in distinct heat ranges, resulting in the brilliant gradients of the hot spring.
It is a drizzly morning when we view the spring from the main boardwalk. The entire area is steamy, shrouding much of the colour, and I cannot help but feel disappointed.
For a better view, we go off the beaten track and drive south to the Fairy Falls trailhead, where we hike and divert onto a nondescript mud trail, scrambling up the side of a hill.
United Airlines flies from Singapore to Jackson Hole Airport, Wyoming, as well as Yellowstone Regional Airport in Cody, Wyoming. Both routes have stopovers in Tokyo and Denver. From either airport, rent a car to explore Grand Teton and Yellowstone National Parks.
We flew into Jackson and out of Cody on domestic flights connecting other cities in the United States.
At the summit, a resplendent perspective of the pool awaits us. The skies are clear, with the sun illuminating the area, and we photograph the breathtaking colour gradations ranging from ochre to turquoise.
We head to Lower Falls, a thundering waterfall set in the Grand Canyon of Yellowstone, a deep chasm with a salmon-pink and creamy beige palette, a result of iron oxidation in its rhyolite rock. With its dramatic 93m plunge, it is close to twice the height of Niagara Falls.
This is the sight that convinced Congress in 1872 to establish Yellowstone, the world's first national park, a ranger informs us, as we assemble our tripod and camera equipment at Artist Point.
Yellowstone was later stewarded by the National Parks Services, which marks its centennial next year.This has earned the US a coveted spot in the new Lonely Planet list of Top 10 destinations for next year.
We join hordes of tourists to witness an eruption at Old Faithful geyser, the most-visited attraction in the region.
A white plume of scalding water launches into the vivid blue sky. Visitors burst into applause and camera shutters go into overdrive.
Old Faithful is not the largest geyser, but it is the most predictable, I tell my husband, suddenly recalling factoids from my Secondary 3 geography class ages ago.
"The geyser erupts once every 35 to 120 minutes and rangers can accurately predict 90 per cent of all eruptions within a window of plus or minus 10 minutes," I rattle on, feeling Hermione Granger-esque.
"Your teacher will be very proud," he says with a grin.
There are smaller thermal pools worth zooming in on, such as the Beauty Pool and Morning Glory Pool, both so beautiful and inviting with mustard, jade and emerald hues. But the pools are also fatally seductive. A ranger recounts how a 24-year-old Californian dove into the scalding waters of the Celestine Pool in 1981 in an attempt to save his friend's dog, which had plunged headlong for a swim. Both died.
Not to be upstaged by the geysers, the animal kingdom in Yellowstone proves equally compelling. Although wildlife roams everywhere, we are most successful in our attempts to spot animals in Lamar Valley and Hayden Valley in Yellowstone.
Known as the "Serengeti of North America", Lamar Valley, near the north-east entrance of Yellowstone, is a beautiful, open landscape that is a magnet for wildlife.
We arrive at dawn and are welcomed by herds of bison and their calves.
A massive bison, with a shaggy chestnut coat overlaying its distinctive hump, ambles across the road. It is slow and placid, but I am reminded that the beasts can weigh up to 900kg and run thrice as fast as humans.
"No selfies," my husband quips, smiling but fully serious.
A coyote, also known as the "song dog", releases a lone howl and races across the meadow.
A pronghorn, whose dual white stripes on its neck contrast with its tawny hide, stops in its tracks. I click my shutter.
The slender animal is still and stares directly at us for several seconds, as though waiting for me to frame my shot, before sprinting off nimbly across the grassy plains.
Hayden Valley, in the east-central region of Yellowstone, is a celebrated area for the wolfspotting fraternity. Their camouflage outfits and fancy telescopes make them easy to spot.
A friendly canid enthusiast offers me the use of her powerful spotting scope and I see a black wolf and two grey wolves circling an area in the horizon.
Wolves were reintroduced to Yellowstone in 1995, she tells us helpfully. As apex predators, they are important animals in the local ecosystem.
The wolves are too far to be photographed with my 300mm lens, but I am ecstatic to have spotted the elusive creatures.
Throughout the year, herds of elk congregate at Mammoth Hot Springs, a mineral-laced area with exquisite layered terraces.
Rangers point us to the fresh green grass by the nearby lodges. The manicured lawns are elk territory and they know no fear of people.
Autumn is prime mating season for elk, with the bulls' antlers fully grown and distinguished to attract females for breeding.
There is no lack of theatrics and there is always something going on.
Bulls are bugling loudly, in their utmost efforts to display absolute dominance. One thrashes its antlers against a tree trunk to polish and darken its tips, while another herds its harem in a most territorial fashion.
The males are extremely aggressive this season. We witness a showdown between two antlerlocking bulls, a fierce match with formidable headgear and intense sparring.
The larger one wins, staking its ground, and the other retreats into the distance.
GRAND TETON LANDSCAPES
There are taller mountains in America, but we discover unparalleled beauty in the ruggedness of the Grand Teton range. The mountains rise majestically from the valley floor and their stately pinnacles are projected onto the surfaces of calm rivers in the foreground.
About 8km from Moose Junction along Highway 191, we discover a narrow gravel road called Schwabacher's Landing.
It is unpaved when we visit and the ride is far from smooth, but we drive slowly and reach a part of Snake River that displays a prime photo opportunity - a reflection of the Cathedral Group of mountains.
Nearby is the famous Oxbow Bend, which presents a mirror image of Mount Moran and its surrounding peaks. At sunrise or sunset, the orange glow of the sun casts its magic on the scene.
A wild black stallion gallops majestically across the plains, trailed by two chestnut horses cantering behind it, conjuring images of the Wild West. We are told later that technically, these are feral horses. Truly wild horses - those not descended from domesticated stock - are extinct in the US.
Off Antelope Flats Road, about 1.6km east of Highway 191, stands the Mormon Row, one of the most postcard-worthy areas of Grand Teton National Park. We arrive with other photography aficionados at dawn, with the rays of the rising sun warmly bathing the sides of the barns and mountains.
Mormon settlers first developed homesteads here in the early 1900s. The buildings were left to decay until the 1990s, when their cultural value was recognised and the barns preserved. The setting is rustic, with the old wooden homesteads - known as the Moulton Barns - standing in open fields, flanked by the serrated peaks of the Grand Teton range.
FIFTY BEAUTIFUL MILES
It is noon on our third and final day when we are ready to tear ourselves away from the parks and make our way to the airport.
Our flight out is from Cody, Wyoming. We exit via the East Gate of Yellowstone into Wapiti Valley, or the Scenic Byway of Highway 20, and we discover why former US president Theodore Roosevelt called this route the 50 most beautiful miles in America.
The Scenic Byway follows the relief of a precipitous landscape, meandering along the winding course of the Shoshone River and soaring over mountain passes. At charming riverbanks, anglers cast their fly for trout.
"The things we will remember most about this trip," I remark, "may be the things we hadn't set out to remember."
Almost on cue, a small herd of bighorn sheep appear without warning, navigating the mountainous terrain ahead of us.
We stop the car at a pullout and watch the grey sheep confidently zig-zag up and down the narrow rocky ridge, their massive curled horns perched above their muscular bodies.
It is a serendipitous moment for which I lay down my camera to savour in silence, feeling dwarfed again by nature.
•Denise Lim is a freelance writer.
•Visit in autumn to avoid summer crowds and peak-season rates. September is ideal - enjoy crisp weather, sights of rutting animals and the bonus of fall foliage.
•A seven-day entrance pass a vehicle to both Yellowstone and Grand Teton National Parks costs US$50 (S$70). Aim to spend a minimum of four days between these two parks and do not underestimate the vastness of each.
•Pre-dawn, mid-morning and late evening are best for viewing wildlife. Animals tend to be more active and the lighting is desirable.
•Keep a safe distance from wildlife - about 90m from bears and wolves and 25m from other large animals such as bison and elk.
•Take along or rent a telephoto lens with a focal length of at least 300mm to get good shots of wildlife without risking your life or disturbing the animals. We had a seamless experience renting our hefty telephoto lens from the United States-based Lens Pro To Go (www.lensprotogo.com; US$122 or S$170 to rent a Canon 28-300 F/3.5-5.6L IS over five days, including shipping). For travellers, lenses can be delivered to hotels in the US, assessed on a case-by-case basis. To return the lens, affix the return label and drop it off at any UPS store in the US.
• Stay on the boardwalks surrounding the geothermal features, which may be above boiling temperature and can cause fatal burns.
A version of this article appeared in the print edition of The Sunday Times on November 08, 2015, with the headline 'Wild, wondrous Wyoming'. Print Edition | Subscribe
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