The call of the wild - and, more specifically, the creatures found in it - is a mighty powerful one.
You don't have to be animal crackers to appreciate the majesty of a whale breaching, a lion stalking its prey or gigantic shoals of tropical fish flitting across a reef.
Yet this fascination with wildlife is hardly a new thing.
Charles Darwin found the Galapagos Islands had an irresistible siren call, while reports of platypuses and kangaroos from early European explorations of Australia piqued the interest of London's chattering classes.
Some travellers are willing to go to great lengths to get close to wild animals, trekking for days to see gorillas , while others are happy to hop on a dolphin-watching boat.
But our joy at seeing creatures in their natural environment isn't necessarily shared by the animals themselves - and there is increasing pressure for wildlife tourism operators to behave responsibly. STA Travel recently stopped selling tours that go to the notorious Tiger Temple in Thailand, a place long the subject of reports of mistreatment, while Intrepid Travel is no longer selling elephant rides as part of its tours.
Unfortunately, there is no single, globally accepted code of conduct for responsible wildlife tourism.
The World Wildlife Fund recommends checking whether the operator can provide a list of trip-specific minimum impact practices, and checking whether they have been verified by a third party such as Sustainable Travel International (STI). The Federation of Tour Operators - now part of ABTA - has a series of recommendations.
These include not feeding or touching the animals, nor acting in a way that makes them behave unnaturally. The very best wildlife experiences shouldn't just be about ogling, though. We've picked our choice of accessible and not-too-obvious adventures that do more than just show you the natural world - they make you think about how it works, and perhaps alter your perspective.
Hluhluwe-iMfolozi Park safari, South Africa
When a teen male elephant stands in the middle of the road, looking mighty stroppy, you suddenly set aside any idea that your safari vehicle gives you superior status.
Hluhluwe-iMfolozi, Africa's oldest game reserve, is one of the best places in the world to spot the traditional Big Five. Leopards, lions and buffalo can be found once the elephant traffic policeman lets you past, but it's the rhinos that are the resounding success story.
In the 1890s, there were about 20 white rhinos left in the world - all of them found here. There are now more than 1500 in the park, and many more have been transplanted to other reserves across Africa.
If ever you need an example of how conservation projects can have a staggering effect, this is it.
Insider tip Hluhluwe-iMfolozi is regarded as low risk for malaria, and anti-malarial medication is generally only advised between November and March. Go between April and October to avoid tablet hassle.
Need to know Ease of access is one of the park's trump cards - it can be visited in a day trip from Durban. Book through Viator from $199. See viator.com.
Monterey Bay cruise, California
Heading out to Monterey Bay should force a rethink on any sepia-tinged views of wild animals being good-natured and gentle. In particular, you should probably abandon Free Willy-induced ideas about the niceness of orcas.
They're called killer whales for a reason, and if they get hold of a seal, they will toy with it and tear it apart for sport, passing it between the group as it struggles to escape.
Less brutal wildlife encounters are also available on Monterey Bay, which owes its status as a wildlife hotspot to the massive canyon running beneath it. Humpback, grey and blue whales drop by at various times of the year, while there's a permanent dolphin population.
Insider tip There are numerous cruise operators on Monterey Bay, but Sanctuary Cruises goes out for longest, with smaller groups and a qualified marine biologist on board to explain things. Keep an eye out for the super-cute sea otters that hang out near the marina.
Need to know Departing from Moss Landing, about 160 kilometres south of San Francisco, the four hour cruises cost US$50 (NZ$59). See sanctuarycruises.com.
Zealandia, Wellington, New Zealand
Not all urban wildlife experiences are quite so dystopian. In Wellington, a 225 hectare valley is home to one of the most remarkable conservation projects. The aim is to restore the valley to how it would have been before humans arrived in the country - which, by the time the giant kauri trees have fully grown, will take 500 years.
A nearly 10-kilometre-long, predator-proof fence has been built around the reserve, and endangered creatures are being reintroduced.
Foremost among these is the lesser-spotted kiwi, of which there are thought to be fewer than 2000 in existence. As night falls, Zealandia's reintroduced kiwis come out to play, bobbing along the paths by the old reservoir, issuing their shrill mating calls.
They're delightfully comical - and, thankfully, safe from the human-introduced mammalian predators that nearly wiped the species out.
Insider tip The reserve is open to the public during the day, but most of the creatures you'll want to see are nocturnal - so go for the guided night-time tours.
Need to know General entry costs $17.50, and the guided night tour costs $75. See visitzealandia.com.
Dolphin kayaking, Byron Bay, Australia
On a dolphin-watching cruise, the joy tends to come when the dolphins sidle up to the side of the boat and start to play in the wake.
If that makes the heart flutter with joy as you peer down from the side of a massive catamaran, then the feeling is multiplied tenfold when you're up close and at the same level in a kayak.
About 300 dolphins, mostly bottlenose, call the waters immediately surrounding Byron Bay home. Responsible tourism etiquette decrees that the kayakers shouldn't approach the dolphins at close range, but that doesn't seem to matter - the dolphins are curious enough to approach the kayaks.
And sometimes, if they're in the mood, they'll flit underneath, playfully breaching on the other side.
Insider tip Go between May and November, and you've a decent chance of seeing whales too. Humpbacks come into the bay for calving, and the calves sometimes get inquisitively close to the kayaks.
Need to know Three-hour tours with Cape Byron Kayaks cost A$69 (NZ$75.75). See capebyronkayaks.com.
Penguin Place viewing trenches, Otago Peninsula, New Zealand
Sometimes, even the most noble of human efforts come undone at the hands of other creatures.
At Penguin Place, a conservation area on an Otago Peninsula sheep farm, the problems come in the form of the honking great sea lions on the beach. They've a nasty habit of picking off the yellow-eyed penguin chicks.
There are only about 4000 of the species remaining, with the Otago Peninsula one of their last remaining habitats. From a system of trenches, deliberately designed to be unobtrusive, a few hardy breeding pairs can be watched scuttling in from the sea after a hard day's fishing.
Insider tip Turn off phones, and stay quiet - viewing is much better when the penguins aren't disturbed.
Need to know Monarch runs a full day trip, including a visit to Penguin Place, a wildlife-viewing cruise on Otago Harbour and a visit to the Royal Albatross Sanctuary, for $235. See wildlife.co.nz; see penguinplace.co.nz.
Yellow Water cruise, Kakadu National Park, Northern Territory
Once you see a croc lying in wait, it's impossible not to appreciate the majesty of these ruthlessly honed killing machines.
They'll watch their prey, over days if necessary, learning their behaviour patterns and feeding times.
And they'll strike when they're certain of success.
Inside an old buffalo wallow, its previous occupant probably turned into a hearty lunch by now, a four metre-long saltie awaits.
"He owns the area," says the guide, pointing to the croc. "He will eat his own brother, sister, uncle and aunt to make sure it stays that way, too."
While wedge-tailed eagles and whistling kites fly overhead and snakes swim sinuously between lily pads, the other crocs sun themselves. Everything else - whether the herons in the mangroves or the egrets skipping along the grassy banks - knows who's in charge.
Insider tip There are six cruises a day, but it's worth getting up early for the 6.45am sunrise departure - it goes for two hours instead of 90 minutes, and it's prime time for active birdlife.
Need to know Departing from the Gagudju Lodge in Cooinda, the cruises cost between $A72 (NZ$79) and A$99. See gagudju-dreaming.com.
FIVE MORE WILDLIFE ADVENTURES
The big white beauties come right up to the specially designed Canadian tundra buggies in Churchill, northern Manitoba. See everythingchurchill.com.
WEEDY SEA DRAGONS
These deeply weird fish - think an ultra-flamboyant version of a seahorse - hang out off the Mornington Peninsula. Bayplay shows them off on snorkelling tours. See bayplay.com.au.
At night on Oman's Ras Al Jinz beach, watch pregnant loggerheads struggle up the sand, dig a hole and deposit their eggs. See nomadtours.com.
The Rimba Orangutan Lodge, accessible only by boat, is right on the cusp of Borneo's Tanjung Putting National Park - arguably the best place to see the noble orange apes in the wild. See ecolodgesindonesia.com.
Fancy snowshoeing through forests with expert trackers in the hope of seeing wolves pad across frozen lakes? Head to central Sweden. See wildsweden.com.
TRAINING THE HUMANS: WHAT TO WATCH FOR
Here are some questions and answers, developed by Intrepid Travel, along with World Animal Protection, to help travellers support tourism that does not exploit wild animals.
Q Does the animal have food and water?
A Many wild animals used to entertain tourists, such as elephants and monkeys, are forced to work long hours with limited access to fresh water and food. They may suffer heat stress, exhaustion and dehydration.
Q: Is there rest and shelter for the animals?
A Wild animals used to entertain tourists have often been taken from their natural environments. They may be kept in enclosures with little or no protection from harsh weather, and may not be given adequate rest.
Q Is this animal in pain and suffering?
A Many captive animals may be suffering from poor nutrition and health, caused by an inadequate diet or access to little or no veterinary care. Some animals may have their teeth pulled or claws clipped, causing terrible suffering.
Q Will I see animals in distress?
A Performing wild animals in zoos, shows and circuses often suffer from high stress levels and psychological trauma caused by close confinement, inadequate conditions and cruel training methods. It's the cruelty you don't see that can be the most distressing thing of all for the animals.
Q Is this "natural behaviour" or is it cruelty?
A Captive animals are often taken from their families. Many animals have complex social structures that cannot be recreated in captivity and are exploited for entertainment, to perform unnaturally.