Tale from the riverbank: Marius Els with his pet hippo Humphrey at his farm in Free State, South Africa
The hippo is most dangerous animal in the whole of Africa.
But they're not all bad - as these incredible pictures show.
A South African farmer has developed a friendship with one that is so trustworthy, the hippo helps him cross lakes on his 400-acre farmstead.
Marius Els breeds 20 different species of wildlife on land near Petrus Steynlakes, including giraffe, buffalo, rhinos and antelope.
But he has a real soft spot for Humphrey, whom he bought aged just five months and allows to roam free. He even built a dam to create a 200m wide and 18m deep lake that is perfect for wallowing in.
The gargantuan pet is now six, and as Marius, 40, explains, 'could rip a man my size apart with no problem'.
Sometimes he does get tired of his ferrying role. 'If he decides to get me off his back, then he throws me over like a horse.'
However, it is usually a case of Marius clinging on for dear life as Humphrey plunging through the water like like a giant grey tank .
The powerful hippopotamus, who at 1200kg weighs well over a metric tonne, is such a strong swimmer that the water barely reaches Marius' knees before they ride to the far side of the lake where the two sit down for a well deserved break.
'Humphrey's like a son to me, he's just like a human,' said Marius,
'There's a relationship between me and Humphrey and that's what some people don't understand.
Balancing act: Marius manages to stay on Humphrey's back as he cadges a lift across the river with the tame hipp at his farm in Free State, South Africa
'They think you can only have a relationship with dogs, cats and domestic animals.
'But I have a relationship with the most dangerous animal in Africa.'
Marius puts Humphrey in a good mood before they ride out together by feeding him copious amounts of his favourite treat, apples.
He also makes sure to allow the happy hippopotamus plenty of time to relax.
Marius' wider social network shows a mixed reaction towards this touching tale of man and beast's unique bond.
Across we go: Marius Els bought Humphrey when he was just five months old and is looking for a mate but tame females are hard to come bywith his pet hippo Humphre
'My friends won't even go near him,' he said..
'My wife, Louise loves Humphrey though, and she worries about him if we don't see him around for awhile.
'But she tells me not to trust him all the time because he is very dangerous.'
Humphrey may be loved by his human owners but the lone hippo still pines for companionship.
'At this stage Humphrey is very alone,' said Marius.
'He had a goat friend, but a jackal killed the goat so he had no other friends after that.
Best friends: Marius pats the back of 1,200kg Humphrey who is so powerful he could rip a human apart in an instant
'I've been looking out for the past three years for a female but it's very difficult to get hold of a tame hippo female, there's none in Africa available.
'I can't put an untamed female with him because the untamed hippo must be less than his age.
'Otherwise they will kill each other.
'So at this stage there is no female hippo that's tamed for Humphrey.'
Humphrey could not now be released safely into the wild to meet females because male bulls would fight and probably kill him.
Instead, Marius is happy to consider any opportunities for long-term relationship prospects with a nice tame female for his hippopotamus son.