The noise that a hippopotamus makes is something that, once heard, can never be unheard. It's like a cross between a large dog drowning and a seriously malfunctioning whoopee cushion.
Experienced in a zoo it's quite amusing, a wet snort that might have come from behind the bathroom door when your father is washing his face and clearing his nose at the same time. Well, my dad, anyway.
In the wilds of Africa, though, when you are balanced in a narrow dugout canoe slung low in the water and surrounded by tall reeds, it's another kettle of 1500 kilogram killing machine. Suddenly that moist flatulence is less than amusing. And it's getting closer, isn't it? I'm sure it's getting closer.
I'm keeping this all to myself, of course. There's no point telling the local guide, who is poling me through a section of water by the Xudum (pronounced Kudum) Okavango Delta Lodge, that in my mind I'm already in the water being chomped on by an animal that is, according to online sources, "a highly aggressive and unpredictable" beast that slaughters more people than any other land animal in Africa.
In the other dugout, or mokoro as it is known here, a stupidly relaxed Dutch couple are smiling and taking pictures while their guide is poling with what strikes me as a studied nonchalance, under which I am certain lurks utter panic at the crazed hippo which even now is powering through the water to slaughter the interlopers in its territory.
I could be wrong. I also know I would never live down the ignominy of being killed by a vegetarian.
There's something truly magical about the Okavango. Just the name is enough to evoke a watery wonderland full of exotic birds, crocodiles, elephant, zebra, antelopes and psychopathic hippos.
The facts say it's a river of southwest-central Africa which flows 1600 kilometres from central Angola to the squelchy section of northern Botswana known as the Okavango Delta. It's an area that was voted the planet's 1000th UNESCO World Heritage site in 2014.
Each year seasonal rainfall in Angola produces a surge of water along the Okavango River which reaches the delta and spreads out over 15,000 square kilometres. With less than a two-metre height variation over the whole area the water slowly evaporates in the heat – but not before swelling the delta to three times its permanent size and attracting wildlife from kilometres around.
Okavango, I understand, means Place of Horrible Hippos in the local bushman dialect. Or it should do.
But enough facts and figures, let's get back to the terrified white man in the rudderless mokoro who is doing his best to take his mind off the fearsome beasts lurking in the reeds by photographing a minuscule green frog which has leapt into the canoe and is gently pooing on his cargo pants. Whether this sort of thing will happen IN the cargo pants is touch-and-go at this point.
There! There's that sound again. Or not. This little bellow isn't from a hippo but from a large bull elephant which, as we round a bend in the waterway, is standing knee deep ahead of us doing whatever elephant do during a pre-sunset paddle.
With murderous hippos behind and an almost certainly ready-to-rampage bull elephant in front we take the sensible option and get out of the canoes to look at a tree. It's a strangler fig and our guides reveal many interesting snippets about it, all of which go in one ear and out the other, skating on a wafer thin coating of fear of getting back into that mokoro.
The mokoro, by the way, has been used by the locals for pretty much ever, though the traditional wooden canoes have made way for fibre-glass replicas which, if jammed sideways in the gaping maw of a hippo, will give you ample time to swim to safety through the crocodiles.
Of course, I am joking (sort of) and we are soon back in the canoes and heading across the lagoon away from the reassuringly fainter and fainter cries of Hippopotamus amphibius.
Then one of the guides spots something dark poking up from the water ahead of us. It is, he says, the bloated corpse of a dead hippo. This, I think, is how one's hippos should come when one is in a mokoro or indeed any boat without an outboard motor or a harpoon.
It's not to be, however. The guides are joshing with us and what emerges through the reeds and the lily pads with their proud white flowers is an inflated black inner tube containing an ice bucket, glasses, a bottle of champagne, soft drinks and a few nibbles. It's amazing how quickly one's fear and bloodlust can be assuaged with a glass of bubbly and a peanut.
A day or two later I hop on a light aircraft for the 10-minute flight to Nxabega Okavango Tented Camp, Xudum's sister lodge which is in a part of the delta that has permanent water coverage. Like its sibling, Nxabega is luxury itself, the rooms, the food and the service second to none. Unlike Xudum, any attempt to actually pronounce "Nxabega" in the clicks and swallowed consonants of the local dialect will result in lockjaw or tongue hernia.
Here, we take to the water again but this time for a sunset powerboat cruise. I am starting to realise that the water is one of the best ways to see the soggy expanse of the Okavango. Not that the daily land-based safaris are anything to be sniffed at as we've already seen our fill of zebras, antelopes, a pride of lions and even a leap of leopards chowing down on the bloody remains of something vaguely beige.
AK is our guide for the sunset … I hesitate to say "cruise" because that suggests something altogether more sedate than this wild, skimming rush across the delta and in and out of its various fingerlike channels.
On the journey AK points out pied kingfishers, African darters, black crowned night herons and a brown snake eagle. Of this last sighting AK explains: "Look at its eyes. They are yellow, which means it's a juvenile." EYES? Is the man part-eagle himself?
Eventually we make our way to a broad, round offshoot of the main delta and moor up just as the afternoon turns to dusk. Here, under a sky slowly turning flamingo pink and sapphire blue as a burnt orange sun heads towards the horizon, AK serves up a host of information about Botswana and the delta alongside several large and civilised G&Ts.
After a while he falls silent and looks about him. "This," he says without fervour but with the confidence of a man who simply knows he's right, "is paradise."
After which we sit there in silence as the evening penumbra deepens, listening to the happy plick-plock sound of frogs in the reeds and the cracking of ice in our glasses.
Motoring back at high speed, the waters turning scarlet under the final hurrah of the sun, a large black shape surfaces off to our left and snorts irritably. "Hippo," I say, as nonchalant as a native in a mokoro.
The Africa Safari Co arranges all flights and transfers, we were on South African Airways which flies from all major Australian cities to Johannesburg via Perth; see flysaa.com
Visas for Botswana can be obtained on arrival. For detailed information on visas and vaccinations, see smartraveller.gov.au
For details of &Beyond lodges, see andbeyond.com
The Africa Safari Co is an Australian-based agency specialising in tailor-made safaris to Africa. Phone 1800 659 279 or see africasafarico.com.au
Keith Austin was a guest of &Beyond and The Africa Safari Co.