It lurks just inches below the surface coiled and ready to strike - and yet you wouldn't know it was there.
These remarkable images show the enormous 26-foot (eight metre) anacondas of Mato Grosso in Brazil searching for prey in the murky depths.
They were captured by brave diver and snake enthusiast Franco Banfi, 53, who joined the beasts in their natural habitat armed only with a camera.
Ready to strike: Brave diver and snake enthusiast Franco Banfi captured this image of an enormous anaconda snake lurking beneath the surface of a river in Mato Grosso do Sul, Brazil
Hunting: This anaconda scans the surface of the water looking for prey such as mice, fish or birds AND HUMANS*
*commentary added by babymilo36
Enormous: This coiled anaconda was about eight metres in length. Swiss diver Franco Banfi captured the photographs on a ten-day visit to the Mato Grosso do Sul region in Brazil
In another shot, Banfi gets up close to a huge anaconda that is lying on the riverbank and glistening in the ferocious tropical heat.
Thankfully for the photographer, it had just gobbled up a capybara rodent and wasn't interested in devouring him as a second course.
Banfi, a father-of-two from Switzerland, said: 'As the snake had just eaten it didn't take much interest in us.
'Everything is possible but I don't think it would have eaten us. I was very close, I could have touched it if I wanted to.'
Time for your close-up: Banfi was able to reach out and touch this massive anaconda sunbathing on the riverbank having devoured a capybara rodent
He saw six different female anaconda snakes on his ten-day trip to the Mato Grosso do Sul region, right in the heart of South America.
The region is known for its diverse natural beauty and attracts thousands of visitors every year.
The name literally means 'Thick Forest of the South' and it's easy to see why.
Banfi added: 'At the first moment it's scary because you don't know the animal and everybody says it's dangerous.
'But after a while you understand that nothing happens if you respect the snake.
'I have never been so close to a snake like this before. But I think a small poisonous snake is more scary than a big one. At least you can see the anacondas clearly and know what they're doing.'
Say cheese! Banfi, 53, goes up close to take an underwater shot of one of the anacondas. He saw six huge female snakes during his time in Brazil
On the prowl: The bright sunlight suggests this anaconda is close to the surface and about the attack
Elegant: This smaller snake glides through the waters