Never smile at a crocodile, they reckon. But blowing bubbles at them is another thing entirely, James Shrimpton, of AAP, reports.
Adventurers are flocking to experience 15 minutes in a "Cage of Death", sharing a large glass tank with a 700kg crocodile at Crocosaurus Cove in downtown Darwin.
And a guidebook features a two-page photograph of a toothy-grinned croc under the caption "Pleased to eat you".
But fear not!
The Cage of Death, holding two swimmers at a time, is designed to give you the thrill of your lifetime, not to end it.
It is fabricated from acrylic-strengthened "glass" that reptiles' jaws and claws cannot break - although the cage bears scars where they've tried.
The nearly 3m-high cage is filled about 75% with water, topped by a grid-roofed section containing air, so the adrenaline-charged swimmers can float up to breathe when required.
The croc divides his time between snoozing on the tank floor and circling the cage as its occupants wave at him - or at the watching spectators and their cameras.
The Cove's seven star crocs, on show in various pits and pens, include 700kg, 5.1m-long Burt, who appeared in the film Crocodile Dundee - Paul Hogan saved co-star Linda Kozlowski "from being eaten" (the guidebook says) after Burt leaped at her from a Northern Territory river.
If the croc doesn't like the invaders in his tank, "there's a good chance you'll receive a very `toothy' reception," viewers are warned.
But the safety record here is 100%, we were assured by Sue O'Loughlin, our Crocosaurus Cove guide.
The cage has proved a hit with everyone from teenagers to octogenarians.
As for the crocs, each has its own personality.
Burt is described as "a movie star with attitude and a reputation with the ladies" although now 80 years of age - the lifespan of saltwater crocs is roughly the same as that of humans.
Snowy is a comparatively rare albino croc, lacking the dark pigment that protects many animals from the harmful effects of the sun.
At 600kg, he is the largest of his kind in captivity.
Chopper, another 80-year-old who is the Cove's largest at 5.5m and 790kg, was captured after reportedly becoming "a little too friendly" with locals at a cattle station 150km west of Darwin.
He is missing his two front feet, lost in fights.
Bruce, "the most eligible (but chauvinistic) bachelor" with the nickname Romeo, bullied both females and males at the Darwin Crocodile Farm, 46km south of Darwin, and was placed in solitary before settling into a bachelor pad at Crocosaurus Cove.
Like Bruce, he is missing part of his body - 30cm of tail.
Big, bad and ugly Denzel has faced the ignominy of being dropped from the breeding programme for continually "shooting blanks" - the eggs he fathered were infertile.
On a more lovable note, there's a "happy honeymoon couple" - Houdini, who earned his name after escaping from one pen to another, and his sweetheart, the lovely Bess.
She's a tiny 2.8m and 90kg whereas he is a beefy 4.6m and 660kg, so "the testosterone needs to be tempered a little to ensure we hear the pitter-patter of tiny feet," the guidebook says with admirable delicacy.
While 15 is the minimum age for human occupants of the cage, there is also a small pool, mainly for youngsters aged 3 to 14, who are separated from the croc enclosure by walls of acrylic glass.
The Cove has lots of other crocodiles on view, from hatchlings to monsters, and it is quite safe to hold a small croc for a photograph, keeping one hand firmly under the jaws (which are held together by rubber bands) just in case.
At feeding time in open pits, spectators see the crocs' menacing side as they bite at chunks of meat offered on long poles by attendants.
On view is the white skull of a croc named Old Charlie, who was shot twice and axed by fish-poachers after becoming entangled in their nets; one bullet remains in his skullbone.
Apart from the collection of crocs, the Cove has a 200,000-litre, two-storey aquarium holding lots of the Northern Territory's favourite fish, barramundi, and 16 other piscine creatures including archer fish and whip-rays.
It also boasts the world's largest collection of reptiles, divided into daytime and nocturnal sections.
Among them are sinister long pythons, more snakes both venomous and harmless, skinks, goannas and other lizards, turtles and frogs, plus the world's first Gracile gecko hatched in captivity.
Crocosaurus Cove opened in July last year in a popular downtown tourist area of the city.
The Darwin district also has other crocodile parks and attractions.
• The writer flew to Darwin by Virgin Blue for an itinerary prepared by Tourism NT (tourismntnt.gov.au).
