Fifty-two per cent of mined tin is used as solder, holding together the circuit boards and components of today's smartphones, laptops and tablets. With the shipment of smartphones and tablets alone expected to have surpassed one billion and 184 million units, respectively, last year (40 per cent and 53.4 per cent year-on-year growths, according to International Data Corporation), the price of tin has skyrocketed, climbing from US$5 to more than US$23 per kilogram in the past 10 years.

Many of the world's top electronics producers have acknowledged that Bangkanese tin is used in their supply chains. But while Bangka is feeding the global hunger for electronic products, the mining of its tin is having a devastating effect on its environment and its people.

With the global demand for tin constantly exceeding supply, Bangka has become a mining free-for-all, with digging feverishly taking place both offshore and onshore. After 13 years of indiscriminate mining, the island's tropical forests are now pockmarked with thousands of moon-like craters contaminated with acidic water and heavy metals.

The industry was liberalised in 2001 and the local government gave mining and smelting licences to local entrepreneurs. As a result of increased demand - especially from private smelters with no mining rights of their own - the island became overrun with tens of thousands of "informal miners", a term that is used to refer to the pensioners, housewives, former fishermen, youngsters and everyone else who is involved in gathering the metal. According to the Mining and Energy Department of the local provincial government, 30 to 40 per cent of Bangka's population is active in mining, some working in private, licensed concessions, but the vast majority operating in unlicensed areas stretching as far as the eye can see, often in the middle of protected forests. Child labour is rife here, as are injuries and fatal accidents, for which the workers or their families receive no compensation.

After reaching the platforms, the men, none of whom is legally employed, start working at a feverish pace. Three of them dive into water so brown and muddy that it contrasts starkly with the turquoise sea further out from the pontoons. Every 30 minutes, the trio emerge for a 10-minute break, before diving again to the seabed, eight metres below the surface.

The divers each suck tin ore from the seabed through a large, plastic tube connected to a diesel-propelled pump - essentially a large vacuum cleaner. The same engine pumps air down a hose connected to a funnel on the surface, allowing the men below to breathe.

Other suction pipes are operated from the decks of the pontoons, from where workers pound the seabed with long, heavy bamboo sticks to stir the sand and expose the ore.

Once sucked up to the pontoon, the heavier tin ore falls to the bottom of the wooden platform while the sand is washed back into the sea.

At the end of the day, a pontoon can have collected 15kg of ore, worth roughly US$100. Depending on the global price of tin at the time, each miner can earn about US$15 per day, double the average pay of a Bangka farm labourer.

However, "divers are the ones who risk most", screams 31-year-old Huwei Liong, who is struggling to make himself heard over the rhythmic, deafening bangs of a pontoon's pump. The heat is unbearable and made worse by blasts of throat-itching exhaust fumes. Surrounding Liong are thin but extremely fit men, some as young as 14, who are soaked in sweat, sea water and mud.

The pits created by drawing ore from the seabed are deep and prone to collapse, in which case divers can be buried under metres of sand. Now a pontoon owner, Liong survived several cave-ins when he was a diver.

"You get buried suddenly, there's no way to prevent it," he says. "Sometimes it takes 30 minutes or one hour for your mates to bring you to the surface."

Many don't get pulled out in time: according to Walhi, a local environmental association, 53 miners died in Bangka in 2012, almost one per week, although those figures cover lives lost both on land and at sea.

play a dangerous game of hide-and-seek with the police. Malasari Amirudin, 33, and her daughter, Novi Akher, 15, have been working in an illegal onshore mine. The previous evening, police raided the mine and shut it down.

"We have no choice but to wait until a new one opens. It generally doesn't take more than one week," says Malasari, in her spartan house, alongside her daughter and two other female miners.

Once they excavate an inland pit, often with basic tools such as shovels and pickaxes, miners hose the ground. The mud is then pumped through plastic hoses and into simple wooden basins, where the ore is washed clean in the same way that it is on the pontoons.

Malasari, who has been making a living from tin since she was 10 years old, and her daughter have recently come from Pangkalpinang, the capital of Bangka, to collect scraps of tin falling from the washing lines, a job that can earn them about US$20 a day. Like most of the other miners, they have no idea what the tin is used for.

"Those things are expensive," jokes Malasari, when she is shown an iPhone. "We should definitely ask for more money for our tin."

Licensed mining companies are required by law to clean up the land after they have finished mining it, by covering up holes and planting vegetation, but most of the exhausted pits in Bangka, being illegal, are abandoned as they are, the only exceptions being those areas that have been converted into palm plantations. State-run tin company PT Timah, the world's largest exporter of the metal, claims many areas that have been rehabilitated by the company are then dug up again by illegal miners.

While this is partly true, "one of the causes of environmental destruction here is the postponement of reclamation", says Ismed Inonu, vice-rector of the University of Bangka Belitung and an expert on the environment and agriculture. "It should have been done by the companies and the government should have given sanctions [to the ones who haven't complied]."

The environmental situation in the sea is even worse. Hundreds of makeshift pontoons are in operation alongside a fleet of 52 dredgers and other types of ship, belonging to PT Timah and other companies, that are sucking up the seabed.

"Bangka has changed a lot since I was a kid. Ten years ago, the place where we are now was all sea," says Liong, sitting beside a Confucian temple surrounded by a small wood.

The coastline in Rebo has been shaped into a series of small gulfs by the sand dumped by dredgers over the years, locals say. According to a recent study by the university, the dumping of sand and other non-valuable tailings has killed between 30 per cent and 60 per cent of the area's coral reef, forcing fish away from the coastline and harming the tourism industry.

The local government has no plans for sea reclamation, despite the fact that mining companies are focusing more and more on offshore resources, to avoid competing with illegal miners (who, lacking proper equipment, can only operate close to the coastline). According to Inonu, it would take at least 20 years for the coral to reconstitute itself, provided it was not further damaged.

Fishermen are the ones suffering the most from sea pollution.

"Fourteen years ago I could fish within four miles [6.5 kilometres] of the coast," says 41-year-old Tsung Ling Xiao, sitting on the porch of his two-storey house in Rebo. "Now, I have to throw my nets as far as 17 miles away."

Tsung has another reason for disliking mining; six years ago, his 32-year-old brother, Ling Fang, was buried in a landslide while he was working in a pit he had dug just 300 metres from Tsung's house. The two miners working with him survived but Ling Fang did not.

Bangka and tin dates back to the 17th century. In 1814, Dutch colonialists began importing Chinese labourers to extract the metal. Today, the descendants of those labourers inhabit many of the villages scattered across the island.

"Every Chinese village you see in Bangka used to be a mining area," says 36-year-old Bambang Yusman, a businessman whose ancestors arrived in Bangka from China roughly 300 years ago.

Bambang personifies the contradictions of this land: the owner of a tourist beach resort near the town of Sungai Liat, he also runs one of the biggest onshore concessions for PT Timah. Although he has campaigned against the environmental destruction caused by offshore mining, he doesn't seem too concerned about the thousands of open pits dotting the island.

"People here are crazy for mining. Some families destroy their houses just to search for tin below them," he says. "You can't separate tin from Bangka. It's part of the culture, and locals have this faith that nature will somehow heal itself."

Although authorities periodically crack down on illegal mining, allegations of the armed forces profiteering from the trade are rife. On our visit, we spot police and navy officers at sundown, near the tin-weighing area in Rebo, where miners bring their ore. Many of the miners we interview say the officers are there to collect bribes.

Asram Somat goes even further. A friendly 30-year-old from the village of Pemali and a father of two, Asram is one of several middlemen buying tin from illegal miners through an array of private traders. He processes and sells to independent smelters about three tonnes of tin concentrate per week, at an average price of US$16 per kilogram. While his business is regularly licensed, Asram says, he pays one million rupiah (HK$685) per month to the police to avoid "problems".

"Sometimes officers visit me and ask for more [money], aside from the monthly pay," he adds, sitting comfortably in an opulent living room that betrays the state of his business.

With more than 40 smelting companies - although not all in constant operation - Bangka produces 90 per cent of Indonesia's tin. Ninety-five per cent of it is sold abroad, be it in China, Europe or the rest of Asia. Tracing the origin of a particular load is virtually impossible. PT Timah accuses independent smelters of buying tin from illegal miners; according to company data, despite holding more than 90 per cent of tin-mining concessions in Indonesia, PT Timah was able to produce only about 28,000 tonnes of tin in 2012, while private companies managed 70,000 tonnes.

"Some [smelting] companies don't even have mining areas at all but they can export tin," says Agung Nugroho, PT Timah's corporate secretary. "This is totally illegal."

Private companies claim PT Timah also buys illegal tin (an allegation confirmed by a PT Timah concession holder who prefers to remain anonymous but denied by the company) and that the distinction between legal and illegal makes little sense, anyway.

"When 40 per cent of the population is involved in mining, how can you say tin is illegal?" asks an independent smelter, who also wishes to remain anonymous.

In an attempt to rein in the market, the Indonesian government has implemented a new rule: since last August, smelting companies have been forbidden from selling tin ingots directly to clients abroad and now have to deal through a centralised stock exchange in the capital, Jakarta. Solder will become subject to the new law next year. The move, which is supposed to stabilise prices and prevent companies from exporting tin of uncertified origin, has been fiercely contested by most of the independent companies, which accuse the government and PT Timah of trying to monopolise the market. The new rule has forced half of the smelting companies operating in Bangka to close down, but, in the long term, it is also likely to exacerbate an already serious smuggling problem.

Friends of the Earth (FoE) launched a campaign to ask the top mobile-phone manufacturers to take responsibility for the environmental situation in Bangka and spearhead an initiative to improve transparency in the tin supply chain. This was easier said than done because, as a Nokia spokesman explained, the companies "are usually four to eight supply-chain actor layers removed from any mining activities. This makes traceability efforts challenging, and the farther away you are from the source, the tougher it is to exert influence".

However, after months of intense campaigning by FoE, last year six companies (BlackBerry, LG Electronics, Motorola Mobility, Nokia, Samsung and Sony Mobile) acknowledged using Bangkanese tin in their supply chain. Apple admitted doing so in February, having initiated a working group to assess tin production on the island within the framework of the Electronic Industry Citizenship Coalition (EICC), the aim of which is to improve social and environmental responsibility in the global supply chain.

Convened by Dutch organisation Sustainable Trade Initiative (IDH), the Indonesian Tin Working Group also includes FoE and the International Tin Research Institute, which represents the industry. The working group is assessing the tin sector in Bangka through a study, the purpose of which is, according to Monique Lempers, IDH's senior programme manager for electronics, to discover "how to best move forward in terms of finding an appropriate, meaningful industry response to sustainability challenges in tin mining in Bangka". While the creation of the working group is certainly a step in the right direction, serious concerns remain, not least of which is the fact that, being a voluntary organisation, the EICC's companies, which also include BlackBerry, LG Electronics, Philips, Samsung Electronics and Sony, will not be compelled to follow any of the findings or recommendations the working group might issue.

"Not finding a meaningful way to contribute is also a possible outcome," says Lempers.

Moreover, the effectiveness of such an initiative would be significantly hampered should any company that sources tin from Bangka refuse to participate. It is not clear when the study will be complete.

"It will be impossible to stop [illegal mining] in the short term, we have to be realistic," says Yan Megawandi, head of the Planning Department of the provincial government in Bangka. "We first need to create employment for the people, so that they can feed their children."

Constrained by a tight budget, he admits it will be difficult to address the environmental damage already caused by mining.

"We need assistance. I think it is fair to ask it of those who have benefited from our tin," he says. "We don't ask necessarily for money, but for technology, training and assistance, to make our society more environmentally friendly. We have limited human resources."

Inonu issues an even gloomier warning for the future of the island: "The impact of the destruction we are seeing now will last decades, if not centuries. Some species of fauna are already disappearing, as well as some high-quality wood forest plants. If action is not taken now, something really bad will happen to this land."

pontoon workers return to Rebo, crammed into the same wooden boat that took them out in the morning. Exhausted but satisfied, they carry small buckets full of the grey, grainy mineral that dictates their lives.

Once weighed, the tin is quickly taken away by a collector while the miners trudge back to their homes, bamboo, straw and thatched-roof houses that stand a few hundred metres away, between the shore and the forest.

Liong is looking worried.

"Unlike most of the other guys here, I am concerned about the environment in Bangka," he admits, after a long silence. "But I will have to mine for the rest of my life. I don't have any other skill," he says, before speeding away on a small motorbike laden with tin.