At the top of a rocky cliff on the South Korean island of Cheju, several people sit motionless in the lotus position, meditating. They are dressed in shimmering black neoprene, white cotton head covers and old-fashioned, oval masks.
These are the Hae Nyeo female divers, who practise a tough, dangerous profession that has continued for centuries. After meditating they will enter the sea to dive, breath-holding, for shells, tunicates, octopus, crabs, seaweeds - anything on the seabed that is edible.
They hardly ever use boats, simply jumping in from the rocky coastline and swimming sometimes long distances to get to the reefs they wish to hunt.
Today, though, they have a lift aboard the small fishing boat in which I sit. I cannot wait to watch and document the work of these legendary divers, whose way of life is threatened because the young are becoming less willing to take up the Hae Nyeo diving mantle.
As our boat nears the cliff to pick them up, the women take their time to finish their meditation, before getting up. Some make guttural sounds to urge those slow to move.
Once aboard, the oldest diver exchanges a few words with our skipper, to say that the women wish to dive on a reef about 300m out from the shore. Her voice fits her features: harsh and hard, weathered from a life in the sea. The womens faces are tanned by wind and salt water, and there are grey streaks in their hair. They have friendly and open features, and dark eyes full of life.
The equipment of the Hae Nyeo is primitive. A 3mm neoprene wetsuit has replaced the traditional white cotton dress, but the head protection and primitive mask with simple elastic ties maintain ancient habits.
They place their weightbelts well above their midriffs, to give them more weight resistance against which to lift items under water. A hip belt holds a flat piece of metal used to prise shells from rocks.
The prey of the day goes into a buoyed net basket with stiffened circular opening, which also helps support the divers when they swim out to their chosen site.
Before diving, contrary to any diving theory, the women put a waxlike waterproof substance in their ears. We arrive at the chosen spot and the women get into action quickly. The nets are thrown overboard and the female divers jump into the water right behind them.
They spread out in all directions and observe the ground through their masks before diving down into the blue at regular time intervals.
It is at least 2 minutes before each divers head shows up at the surface again. And each time they surface, the divers make a melodious whistling sound - a unique technique of breathing and preparing for their next plunge.
The South Korean underwater world in which the divers hunt is richly diverse. Cold water kelp forests grow on volcanic rocks close to tropical soft corals. Animals, too, contrast notably. Exotic lionfish, for instance, are commonly found next to Atlantic rock grouper.
I enter the water with my camera. A Hae Nyeo diver hovers at the surface 15m above me, and raises her head to take her last deep breath before shooting down head first.
Quick and nimble, fishlike, she glides over rocks, under overhangs and squeezes into narrow openings. Her well trained eyes quickly pick out wanted prey - shells and starfish - and she uses her piece of metal rapidly to detach them. It is amazing how long this woman can hold her breath and work hard under water. Back at the surface she puts the prey in the circle net before heading straight back down for another attempt.
For an hour I observe the Hae Nyeo. Their physical performance is absolutely astonishing, each female diver heading down to depths of up to 20m about 30 times over. The circle nets gradually fill up.
Nowadays, the Hae Nyeo divers are well respected and honoured, but this was not always so. No documents exist about the Hae Nyeo, because historically records of them were forbidden.
The women were not accepted by high society. They were thought to be uneducated, wild, stubborn, much too independent, and the vocabulary they used was considered outlandish. As if this was not enough, they dared to dive into the sea half naked!
The Hae Nyeo have, though, maintained a special community of their own. Their appearance and vocabulary still reflect the fact that they are tough and self-confident women.
Men are not welcome in their community, at least not in their work. Their strenuous and dangerous way of diving, of up to 4 or 5 hours every day, has united them very closely.
Despite their abilities, the female divers do get into trouble. High waves and currents can lead them to complete exhaustion, and through an interpreter I learn that one still-active 70-year-old diver has lost many of her female companions to the sea.
Some, she says, had become stuck while trying to get a shell of extraordinary size out of an opening; and others had been taken away by strong currents.
The worst accident the old female diver remembers is a shark attack, in which a female diver who must have hurt herself badly and lost a lot of blood was tracked down by a big shark and killed.
Soon, says the elderly diver, the female divers will have disappeared for good. Despite the good money to be earned from selling seafood, young girls nowadays dont want to continue the breath-hold hunting traditions of the Hae Nyeo. A way of life that has existed for centuries could soon be gone.