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Next time you say you're going for a quick dip, spare a thought for these guys who take swimming to new depths. Groups of incredibly brave men in Cameroon dive into fast-flowing rivers in search of...sand.
No goggles, no speedos, and certainly no breathing equipment, it is one of the most dangerous jobs in the world.
The muscular workers dive up to 20ft in order to scoop up sand from the river bed, which they then use in the building industry.
And now the amazing feat has been caught on camera after photographer, Hugh Brown, took some candid snaps of the men during one of their excursions, known in Central Africa as artisanal mining.
Artisanal mining is a subsistence miner who is not officially employed by a company, but works independently.
Together they manage to collect around 1.7 tonnes of wet sand from bottom of the Wouri River every time they dive to the bottom.
And what's more amazing, some of the men in these photographs can't even swim properly, yet still make at least 100 trips to the bottom during every shift.
These pictures, which were taken with the assistance of the United Nations Development Programme, show divers using three kilogram steel buckets with holes punched in the bottom.
On reaching the river bottom they then scoop up around 15 kgs of wet sand and then use a pole to launch themselves up to the surface and tip the river-sand into the boat.
Hugh, from Perth, Australia, said: "The work is very very dangerous. Just getting to the bottom and getting sand in the bucket proved to be an incredible achievement - let alone then bringing it up from the river floor.
"They are incredibly tough people that were amongst the strongest and most ripped people that I have ever photographed anywhere around the world."
Around 4000 divers are believed to work along the stretch of water, and Hugh says some of them are 'lucky to be alive'.
The 48-year-old added: "Just the act of diving for them, particularly in these tides, takes incredible bravery.
"Divers are sometimes so exhausted after filling a pirogue that they have no strength left to swim.
"Drownings have also occurred when they end up in the water on the return trip back to port.
"Other divers - that can swim - drown when they misjudge the location of the hull of the boat and get knocked out when they surface and bang their heads.
"At night this is particularly dangerous because no one can see them in the dark and they can get washed away by the tides.
"Other divers suffer from bleeding from the ears and noses and eyes due to the depths they are working at and sand often ingresses through those cavities."
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