EVEN on a warm, late Spring day, with wetsuits beneath their distinctive white costumes, the women look cold as they emerge from the water. It is a reminder that for all the excitement of the ancient mikazuki shinji ceremony they have helped re-enact, Japan's ama diver women have chosen a hard way to make a living.

Usually, after they've dried out around an open fire, the women send their catch straight to the fish market but today they carry their baskets of abalone shells to a small stand on the beach, where a fishmonger expertly slices the flesh within and seasons it with a little soy sauce. Youngsters there to witness the old Shinto rituals of the indigenous faith of their island nation jostle for a chance to taste the highly prized – and highly priced – delicacy.

Later, as the women chat and rest before their next dive, I ask them about their centuries-old way of life. On a cold day, when the seas are rough and the catch is poor, don't they wish they worked in an office? "I've never dreamed of that," says Wakako Okamoto. Her friend Kazuyo Seko chuckles at the question. "No," she agrees. "It's hard to make a living but a good catch makes us happy."

Wakako, who is 63, and Kazuyo, 61, are among 1600 remaining ama divers. They have worked the waters off the Ise Shima peninsula for the best part of 50 years but belong to a declining tradition with fewer younger women taking up the life.

In living memory there were more than 17,000 ama. Since the 1950s, however, their numbers have dwindled. Some blame the dangers and uncertain rewards of the job; Wakako and Kazuyo say their daughters sometimes help them but never wanted to become full-time divers.

Others highlight a sharp decline in the abalones they search for during each "50 second battle" with their own lungs. It started with the invention of the wetsuit in the 1960s, which allowed the women to dive for longer and make record catches, but global warming is now seen as the biggest threat.

After a Shinto priest concludes the mikazuki shinji ceremony, offering prayers for calm seas, and the spectators, local officials and TV crews drift away from the beach, the women wade back into the water carrying bags of juvenile abalones to place on the seabed, a vital part of their new role conserving the stocks.

The ama way of life has long been a source of fascination in Japan, a country where until recently women have largely been confined to traditional roles as mothers and home-makers. They are mentioned in 1200-year-old texts, though the practice is thought to date back millennia. It's not that men never dive, it's simply that women are more successful, their bodies better able to withstand the cold.

Yoshitaka Ishihara, the director of the folk museum in the quiet fishing town of Toba, where many of the remaining ama live and work, is spearheading an effort to gain UNESCO "intangible cultural heritage" status for their way of the life, and it is also something the Japanese government wants to highlight as it prepares to host the G7 summit a few miles away at Kashikojima, an upmarket island resort in the heart of the Ise Shima national park.

At a gathering where the role of women in work will be high on the agenda, what stronger symbol for world leaders to ponder than the lives of the ama divers?

Officially, at least, the venue for the summit was chosen because of Prime Minister Shinzo Abe's keen desire to show the G7 leaders the nearby shrines of Ise Jingu, Japan's most sacred site and a place he visits regularly. Unofficially, of course, there is the issue of security. Just as the relative remoteness of Gleneagles was a factor when Scotland hosted the then-G8 in 2005, so the island of Kashokojima will be easier to police and protect than a big city setting.

Either way, the decision has put an area of Japan largely unknown to the rest of the world in the spotlight and towns like Toba, which has long been popular with holidaymakers from Tokyo, are determined to make the most of the opportunity.

At Hachimankado, a beach-side restaurant just up the road, they are already flying the flags of the G7 nations. "Restaurant" doesn't quite do it justice, though the food is as good as you'll eat anywhere. It is little more than a wooden shack with gauze, not glass, for windows. In the unlit dining room, low benches surround a fire pit that smoulders with a powerful charcoal aroma. Set up by an ama when she retired from diving at the age of 72 (now 84, she still runs the place) it serves up whatever the women catch. On to the griddle the day I visited went prized shellfish and turban shells by the basketful. After a few minutes' roasting they yielded a hot, chewy meat as salty as the sea. It proved that even in a country with the most exquisite cuisine, the simplest food is often the best.

Across Mie prefecture a huge effort is on to highlight the area's rich culture and traditions. At Suzuka, master craftsman Tadashi Ito and his son Harunobu demonstrated the ancient techniques of producing black ink sticks used in calligraphy. Moulded from a clay-like paste made from pine wood soot and animal bone glue, the blocks can be dried for years, intensifying the pigment with age. They are the last traditional producers in a city once famed for a craft that dates back 1200 years, and one of only four remaining firms in Japan. From a small workshop infused with a heady incense-like smell, they explained how they hope to revive the industry by diversifying into dies for the fashion industry and even food colourings.

In an even smaller workshop not far away, wood carver Tadamine Nakagawa discussed the art of netsuke – tiny, intricate and frighteningly expensive toggles used with a kimono and prized by collectors.

On the beautiful island of Toshijima, a 30-minute ferry trip from Toba, members of the close-knit fishing community explained their custom of neyako, in which teenage boys are sent to a foster family to be mentored as they become adults. Once common across Japan, Toshijima is the last place where it practised. Islanders credit the custom with staunching the flood of young people to Tokyo and other big cities – a problem across rural Japan – and keeping their community alive.

For the neyako boys, whose neya-ora, or neya parent is more big brother than strict father figure, the arrangement is great fun. For Takaaki Hamaguchi, a fisherman and neya-ora, it is about putting something back into the community. Inviting us into his home, he said it was a privilege to have been asked by other families, even though it means keeping a bedroom ready for his neyako sons whenever they wish to stay the night.

"I want to be a good person in society and I've been recognised as a responsible parent." he said.

The island's main hostelry, Hotel Suzanami, is an old-fashioned Japanese inn where guests sleep on futons in rooms divided by paper partitions and was an ideal base from which to explore the narrow streets and houses decorated with the maruhachi, a motif inked on the walls, and shimenawa, dolls made from ropes of twisted corn, to bring luck and ward off evil spirits.

Straying off the beaten track revealed a Japan that is a world away from the gleaming skyscrapers and teeming crowds of Tokyo, where ancient and modern seem to co-exist quite naturally. The Ise Jingu shrines – one part of the Mie region which is on the beaten track – unashamedly celebrates the country's ancient past.

Eight million pilgrims a year visit the vast complex of 125 shrines spread over an area the size of Paris. The main shrine was founded by a princess 2000 years ago who, after a long search, discovered the area could provide offerings suitable for the deity Amaterasu-omikami, the ancestral protector of the imperial family and Japanese people. All that makes it Japan's most sacred place.

For more than 1000 years the wooden buildings and most of their contents have been rebuilt from scratch every 20 years, in accordance with strict custom. A hundred priests perform a cycle of rituals that takes eight years to complete.

But the facts and figures tell only a small part of the story. Ise Jingu, set amid acres of woods and rivers, seems to swallow the crowds. To cross the Ujibashi bridge and pass the giant stands of saki barrels lined up in offering to the deities is to enter a place of unusual calm.

If a just little of that rubs off on the G7 leaders as they wrestle with problems of the global economy, terrorism and climate change, Prime Minister Abe's invitation will indeed have been an inspired one.