Which American national park should I visit - Yellowstone or Yosemite?

By Mal Chenu

America does national parks better than most. As historian Wallace Stegner noted: "National Parks are the best idea we ever had. Absolutely American, absolutely democratic, they reflect us at our best rather than our worst."

Whether they represent the best of the US is subjective, but for me, this stands in the pantheon of American exceptionalism quotes somewhere between "that's one small step for a man..." and "they're eating the pets".

Yellowstone became the first national park in the world when President Ulysses S. Grant signed the Yellowstone Protection Act into law in 1872. There are now 63 in the USA and more than 6500 on the planet, so the idea seems to have caught on. Sitting in the top left corner of the sonorously named Wyoming and extending into bits of Montana and Idaho, Yellowstone is a 9000 sq km treasure trove, replete with mountains, valleys, waterfalls, canyons, lakes and rivers of surpassing splendour.

Self-driving is the way to go and five park entrances mean you can plan your own scenic drive route and itinerary. And whichever way you choose you'll be treated to some of the most beautiful scenery imaginable.

Yellowstone is also an International Biosphere Reserve, and is home to grizzly bears, cougars and wolves. Enormous herds of bison and elk dot endless picturesque savannah, while bald eagles, golden eagles, ospreys and peregrine falcons circle above. There are numerous lodges and camping grounds but if opting for the latter, it is important to note that some grizzly bears consider sleeping bags to be burritos.

But Yellowstone's primary come-hither enticement is its unique hydrothermal and geologic features. Yellowstone hosts around half of Earth's geothermal spectacles, with a stunning array of hot springs, mud holes and more than 500 geysers.

Chief among these is the renowned Old Faithful, which shoots up to 32,000 litres of boiling water 56 metres into the air every 90 minutes or so. The Grand Prismatic hot spring has a multi-coloured layering created by hardy species of heat-loving bacteria that live around it. The deep centre is deep blue, blending into green and yellow tints further out, merging into Trumpian orange on the outskirts.

All these geothermal goodies are a product of the thrill-seeking characteristic of the park. You see, Yellowstone is an active supervolcano. Created by a cataclysmic eruption 640,000 years ago, the Yellowstone Caldera magma reserve lurks menacingly below almost the entire park, and could blow at any time. It hasn't gone off in about 70,000 years and some say it is due. A major eruption could discharge more than 1000 cubic kilometres of super-heated volcanic material, so pack some marshmallows to roast on your way out.

By Amy Cooper

While Mal shares his memoirs of a geyser direct from the spurting surfaces of Wyoming, allow me to transport you instead to the spectacular serenity of California's Sierra Nevada. I find Yellowstone's topographical turbulence, with all that churning and expelling, far too hectic. It's hard to relax in a landscape that behaves like the digestive aftermath of a curry buffet. I'd rather bliss out in the vast embrace of Yosemite, breathing in the grandeur of granite domes, giant trees, alpine lakes and mountain ranges glacially sculpted over millennia.

It's a place of such dizzying beauty that 19th-century naturalist John Muir declared it "the highest point in life's journey my feet have yet to touch". Muir knew a thing or two about natural wonders. He sparked the modern conservation movement, and he loved Yosemite so much he persuaded the US president to make it a national park in 1890.

Listen out for Muir's spirit whispering "you're welcome" while you roam his favourite wonderland's 1280 kilometres of wilderness trails, from verdant valley floors through pristine lakes and meadows, up and around those giddy peaks. If you're of a Spiderman disposition, you'll want to scale the vertical face of granite monolith Half Dome or the sheer edifice of 2308m El Capitan, the world's largest single piece of granite. For those who prefer a gentler relationship with gravity, you can hike up many of Yosemite's 30-plus peaks for a reward of heart-stopping views. Mount Hoffman, right at the park's centre, delivers the full 360 across the valleys, lakes, canyons and Sierra Nevada ranges.

Yosemite's mountains are majestic, but its trees are titanic. Giant sequoias are among the oldest and largest living organisms on Earth - like the whales of the woods. Yosemite's Mariposa Grove has hundreds, some more than 2000 years old and over 20 storeys tall. Just last month, one of Yosemite's towering sugar pines was declared the world's largest pine tree. Trunk that, Yellowstone. Yosemite goes big on waterfalls, too. A cavalcade of cascades includes Yosemite Falls, which thunders 739 metres over three tiers.

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While Yellowstone slumbers in winter, Yosemite keeps the fun coming all year round. Right now, it's a crimson, gold and amber vision as autumn works its arboreal alchemy; spring brings wildflowers and snowmelt-swollen waterfalls, and in winter there's family-friendly snow sports at Badger Pass, California's oldest ski resort.

And it's all in the US's most accessible national park. While you're car-dependent at Yellowstone, there's a free public shuttle throughout Yosemite, and train and bus connections to major Cali cities. You're just 3.5 hours from San Francisco, and five from LA, so you can go from tree to sea in one glorious trip.

Forget that dodgy geyser over there - say yo to Yosemite.